To complete the history and analysis of the Scotch mind, I have now to examine the peculiar intellectual movement which appeared in the eighteenth century, and which, for several reasons, deserves careful attention. It was essentially a reaction against that theological spirit which predominated during the seventeenth century. Such a reaction would hardly have been possible, except for the fact which I have already noticed, namely, that the political activity which produced the rebellion against the Stuarts, saved the Scotch mind from stagnating, and prevented that deep slumber into which the progress of superstition would naturally have thrown it. The long and stubborn conflict with a despotic government, kept alive a certain alertness and vigour of understanding, which survived the struggle that gave it birth. When the contest was ended, and peace was restored, the faculties which, for three generations, had been exercised in resisting the executive authority, sought other employment, and found another field in which they could disport themselves. Hence it was, that the boldness which, in the seventeenth century, was practical, became, in the eighteenth century, speculative, and produced a literature, which attempted to unsettle former opinions, and to disturb the ancient landmarks of the human mind. The movement was revolutionary, and bore the same relation to ecclesiastical tyranny, which the previous movement had borne to political tyranny. But this new rebellion had one striking characteristic. In nearly every other country, when the intellect has fairly arrayed itself against the exclusive pretensions of the Church, it has happened that the secular philosophy, which has been engendered, has been an inductive philosophy, taking for its basis individual and specific experience, and seeking, by that means, to overthrow the general and traditional notions, on which all church power is founded. The plan has been, to refuse to accept principles which could not be substantiated by facts; while the opposite and theological plan is, to force the facts to yield to the principles. In the former case, experience precedes theory; in the latter case, theory precedes experience, and controls it. In theology, certain principles are taken for granted; and, it being deemed impious to question them, all that remains for us is to reason from them downwards. This is the deductive method. On the other hand, the inductive method will concede nothing, but insists upon reasoning upwards, and demands that we shall have the liberty of ascertaining the principles for ourselves. In a complete scheme of our knowledge, and when all our resources are fully developed and marshalled into order, as they must eventually be, the two methods will be, not hostile, but supplementary, and will be combined into a single system. At present, however, we are very far from such a result; and not only is every mind more prone to one method than to another, but we find, historically, that different ages and different countries have been characterised by the extent to which one of these two schemes has predominated; and we also find, that a study of this antagonism is the surest way of understanding the intellectual condition of any period.

That the inductive philosophy is even more marked by its secular tendencies than by its scientific ones, will be evident to whoever observes the epochs in which it has been most active, and has possessed most adherents. Of this, the history of the French mind, in the eighteenth century, affords a good instance, where, after the death of Louis XIV., we may clearly trace the connexion between the growth of the inductive method, and the subsequent overthrow of the Gallican Church. In England, too, the rise of the Baconian philosophy, with its determination to subordinate ancient principles to modern experience, was the heaviest blow which has ever been inflicted on the theologians, whose method is to begin, not with experience, but with principles, which are said to be inscrutable, and which we are bound to believe without further difficulty. And I need hardly remind the reader, that scarcely was that philosophy established among us, when it produced those bold inquiries which quickly ended in the downfall of the English Church under Charles I. From that terrible defeat, our clergy did, for a time, partly rally; but as their apparent success, in the reign of Charles II., was owing to political changes, and not to social ones, they were unable to recover their hold over society, and, unless the nation should retrograde, there is no possibility that they ever should recover it. Over the inferior order of minds, they still wield great influence; but the Baconian philosophy, by bringing their favourite method into disrepute, has sapped the very base of their system. From the moment that their mode of investigation was discredited, the secret of their power was gone. From the moment that men began to insist on inquiring into the validity of first principles, instead of accepting them without inquiry, and humbly submitting to them as matters of faith and of necessary belief; from that moment, the theologians, driven from one post to another, and constantly receding before the pressure of advancing knowledge, have been forced to abandon entrenchment after entrenchment, until what they have retained of their former territory is hardly worth the struggle. As a last resource, they, at the close of the eighteenth century, determined to use the weapons of their opponents; and Paley and his successors, enlarging the scheme which Ray and Derham had feebly sketched, endeavoured, by a skilful employment of the inductive method, to compensate their party for the failure of the deductive one. But their project, though ably conceived, has come to naught. It is now generally admitted, that nothing can be made of it, and that it is impossible to establish the old theological premises by a chain of inductive reasoning. Respecting this, the most eminent philosophers agree with the most eminent theologians; and, since the time of Kant in Germany, and of Coleridge in England, none of our ablest men, even among divines themselves, have recurred to a plan which Paley, indeed, pursued with vigour, but of which our Bridgewater Treatises, our Prize-Essays, and such schoolboy productions, are poor and barren imitations.[613] No great thinkers now follow this course in matters of religion. On the contrary, they prefer the safer, as well as the more philosophic, method, of dealing with these subjects on transcendental grounds, frankly confessing that they elude the grasp of that inductive philosophy which, in the department of science, has achieved such signal triumphs.

The opposition of these two methods, and the inapplicability of the inductive method to theological pursuits being thus apparent, it is not strange that the Scotch should have adopted one of the methods with great zeal, and to the almost complete exclusion of the other. Scotland, being essentially theological, followed the theological plan. The intellectual history of that country, in the seventeenth century, is almost entirely the history of theology. With the single exception of Napier, who was born in the middle of the sixteenth century, all the most vigorous thinkers were divines. In physical science, scarcely anything was done.[614] There was no poetry, no drama, no original philosophy, no fine compositions, no secular literature, now worth reading.[615] The only men of real influence were the clergy. They governed the nation and the pulpit was the chief engine of their power. From the pulpit, they moved all classes and all sorts intellects; the highest as well as the lowest. There, they instructed them, and threatened them; saying whatever they liked, and knowing that what they said would be believed.[616] But all their sermons, and all their controversial writings, are eminently deductive; not of them attempts an inductive argument. The idea of such a thing never entered their heads. They assumed the truth of their own religion and moral notions, most of which they had borrowed from antiquity; they made those notions the major premises of their syllogisms, and from them they reasoned downwards till they obtained their conclusions. They never suspected that premises, taken from ancient times might be the result of the inductions of those times and that, as knowledge advanced, the inductions might need revising. They assumed, that God has given us first principles, and that He, having revealed them it would ill become us to scrutinize them. That He had revealed them, they took for granted, and deemed it unnecessary to prove.[617] Their method being entirely deductive, all they were concerned with was to beware that no error crept in between the premises and the conclusions. And this part of their task they accomplished with great ability. They were acute dialecticians, and rarely blundered in what is termed the formal part of logic. In dealing with their premises after they obtained them, they were extremely skilful; how they obtained them, they were very heedless. That was a point they never examined with anything approaching to impartiality. According to their method, all that was requisite was, to draw inferences from what had been supernaturally communicated. On the other hand, the inductive method would have taught them that the first question was, whether or not they had been supernaturally communicated? They, as deductive reasoners, assumed the very preliminaries which inductive reasoners would have disputed. They proceeded from generals to particulars, instead of from particulars to generals. And they would not allow either themselves or others to sift the general propositions, which were to cover and control the particular facts. It was enough for them that the wider propositions were already established, and were to be treated according to the rules of the old and syllogistic logic. Indeed, they were so convinced of the impropriety of the inductive method, that they did not hesitate to assert, that it was by means of the syllogism that the Deity communicated His wishes to man.[618]

It was naturally to be expected, that the clergy, holding these views respecting the best means of arriving at truth, should do all in their power to bring over the nation to their side, and should labour to make their own method of investigation entirely supersede the opposite method. Nor was this a very difficult task. The prevailing credulity was one great point in their favour, inasmuch as it made men more willing to accept propositions than to scrutinise them. When the propositions were accepted, nothing was left but to reason from them; and the most active intellects in Scotland, being constantly engaged in this process, acquired complete mastery over it, and the dexterity they displayed increased its repute. Besides this, the clergy, who were its zealous champions, had monopolized all the sources of education, both public and private. In no other Protestant country, have they exercised such control over the universities; not only the doctrines taught, but also the mode of teaching them, being, in Scotland, placed under the supervision of the Church.[619] This power they, of course, used to propagate their own plan of obtaining truth; and, as long as their power remained undiminished, it was hardly possible that the opposite, or inductive, plan should gain a hearing. Over grammar-schools, the clergy possessed an authority fully equal to that which they had in the universities.[620] They also appointed and removed, at their own pleasure, teachers of every grade, from village schoolmasters to tutors in private families.[621] In this way, each generation, as it arose, was brought under their influence, and made subject to their notions. Taking the mind of Scotland while it was young and flexible, they bent it to their own method. Hence, that method became supreme; it reigned every where; not a voice was lifted up against it; and no one had an idea that there was more than one path by which truth could be reached, or that the human understanding was of any use, except to deal deductively with premisses, which were not to be inductively examined.

The inductive or analytic spirit being thus unknown, and the deductive or synthetic spirit being alone favoured, it happened that, when, early in the eighteenth century, the circumstances already mentioned gave rise to a great intellectual movement, that movement, though new in its results, was not new in the method by which the results were obtained. A secular philosophy was, indeed, established, and the ablest men, instead of being theological, became scientific. But so completely had the theological plan occupied Scotland, that even philosophers were unable to escape from its method, and, as I am about to show, the inductive method exercised no influence over them. This most curious fact is the key to the history of Scotland in the eighteenth century, and explains many events which would otherwise appear incompatible with each other. It also suggests an analogy with Germany, where the deductive method has, for a long period, been equally prevalent, owing to precisely the same causes. In both countries, the secular movement of the eighteenth century was unable to become inductive; and this intellectual affinity between two such otherwise different nations, is, I have no doubt, the principal reason why the Scotch and German philosophies have so remarkably acted and reacted upon each other; Kant and Hamilton being the most finished specimens of their intercourse. To this, England forms a complete contrast. For more than a hundred and fifty years after the death of Bacon, the greatest English thinkers, Newton and Harvey excepted, were eminently inductive; nor was it until the nineteenth century that signs were clearly exhibited of a counter-movement, and an attempt was made to return in some degree to the deductive method.[622] This we are, in many respects, justified in doing, because, in the progress of our knowledge, we have, by a long course of induction, arrived at several conclusions which we may safely treat deductively; that is to say, we may make them the major premisses of new arguments. The same process has been seen in France, where the exclusively inductive philosophy of the eighteenth century preceded a partial resuscitation of deductive philosophy in the nineteenth century. In Scotland, however, there have been no such vicissitudes. In that country, men have always been deductive; even the most original thinkers being unable to liberate themselves from the universal tendency, and being forced to accept a method which time had consecrated, and which was interwoven with all the associations of the national mind.

To understand the investigation into which we are about to enter, the reader must firmly seize, and keep before his eyes, the essential difference between deduction, which reasons from principles, and induction, which reasons to principles. He must remember, that induction proceeds from the smaller to the greater; deduction, from the greater to the smaller. Induction is from particulars to generals, and from the senses to the ideas; deduction is from generals to particulars, and from the ideas to the senses. By induction, we rise from the concrete to the abstract; by deduction, we descend from the abstract to the concrete. Accompanying this distinction, there are certain qualities of mind, which, with extremely few exceptions, characterize the age, nation, or individual, in which one of these methods is predominant. The inductive philosopher is naturally cautious, patient, and somewhat creeping; while the deductive philosopher is more remarkable for boldness, dexterity, and often rashness. The deductive thinker invariably assumes certain premisses, which are quite different from the hypotheses essential to the best induction. These premisses are sometimes borrowed from antiquity; sometimes they are taken from the notions which happen to prevail in the surrounding society; sometimes they are the result of a man's own peculiar organization; and sometimes, as we shall presently see, they are deliberately invented, with the object of arriving, not at truth, but at an approximation to truth. Finally, and to sum up the whole, we may say that a deductive habit, being essentially synthetic, always tends to multiply original principles or laws; while the tendency of an inductive habit is to diminish those laws by gradual and successive analysis.

These being the two fundamental divisions of human inquiry, it is surely a most remarkable fact in the history of Scotland, that, during the eighteenth century, all the great thinkers belonged to the former division, and that, in the very few instances of induction which their works contain, it is evident, from the steps they subsequently took, that they regarded such inductions as unimportant in themselves, and as only valuable in so far as they supplied the premisses for another and deductive investigation. As the various departments of our knowledge have never yet been co-ordinated and treated as a whole, probably no one is aware of the universality of this movement in Scotland, and of the extent to which it pervaded every science, and governed every phase of thought. To prove, therefore, the force with which it acted, I now purpose to examine its working in all the principal forms of speculation, whether physical or moral, and to show that in each the same method was adopted. In doing this, I must, for the sake of clearness, proceed according to a natural arrangement of the different topics; but I will, whenever it is possible, also follow the chronological order in which the Scotch mind unfolded itself; so that we may understand, not only the character of that remarkable literature, but likewise the steps of its growth, and the astonishing vigour with which it emancipated itself from the shackles which superstition had imposed.

The beginning of the great secular philosophy of Scotland is undoubtedly due to Francis Hutcheson.[623] This eminent man, though born in Ireland, was of Scotch family, and was educated in the University of Glasgow, where he received the appointment of Professor of Philosophy in the year 1729.[624] By his lectures, and by his works, he diffused a taste for bold inquiries into subjects of the deepest importance, but concerning which it had previously been supposed nothing fresh was to be learned; the Scotch having hitherto been taught, that all truths respecting our own nature, which were essential to be known, had been already revealed. Hutcheson, however, did not fear to construct a system of morals according to a plan entirely secular, and no example of which had been exhibited in Scotland before his time. The principles from which he started, were not theological, but metaphysical. They were collected from what he deemed the natural constitution of the mind, instead of being collected, as heretofore, from what had been supernaturally communicated. He, therefore, shifted the field of study. Though he was a firm believer in revelation, he held that the best rules of conduct could be ascertained without its assistance, and could be arrived at by the unaided wit of man; and that, when arrived at, they were, in their aggregate, to be respected as the Law of Nature.[625] This confidence in the power of the human understanding was altogether new in Scotland, and its appearance forms an epoch in the national literature. Previously, men had been taught that the understanding was a rash and foolish thing, which ought to be repressed, and which was unfit to cope with the problems presented to it.[626] Hutcheson, however, held that it was quite able to deal with them, but that, to do so, it must be free and unfettered. Hence, he strenuously advocated that right of private judgment which the Scotch Kirk had not only assailed, but had almost destroyed. He insisted that each person had a right to form his opinion according to the evidence he possessed, and that, this right being inalienable, none but weak minds would abstain from exercising it.[627] Every one was to judge according to his own light, and nothing could be gained by inducing men to profess sentiments contrary to their convictions.[628] So far, however, was this from being understood, that we found all the little sects quarrelling among themselves, and abusing each other, merely because their views were different. It was strange to hear how the professors of one creed would stigmatize the professors of other creeds as idolatrous, and would demand that penalties should be inflicted on them. In point of fact, all had much that was good; and their only real evil was, this love of persecution.[629] But the vulgar deemed every one a heretic who did not believe what they believed; and this way of thinking had been too much countenanced by the clergy, many of whom felt their vanity offended at the idea of laymen pretending to be wiser than their spiritual teachers, and venturing to disagree with what they said.[630]

Such large views of liberty were far in advance of the country in which they were propounded, and could exercise no influence, except over a few thinking men. These, and similar doctrines, were, however, repeated by Hutcheson, in his lectures, every year.[631] And strange, indeed, they must have seemed. To those who received them, they were utterly subversive of the prevailing theological spirit, which regarded toleration as impious, and which, seeking to confine the human mind within the limits of foregone conclusions, deemed it a duty to chastise those who overstepped them. In opposition to this, Hutcheson let in the elements of inquiry, of discussion, and of doubt. There is also another point in which his philosophy is memorable, as the beginning of the great rebellion of the Scotch intellect. We saw, in the last chapter, how successfully the teachers of the people had inculcated doctrines of the darkest asceticism, and how naturally those doctrines had arisen out of the enormous authority possessed by the Church. Against such notions, Hutcheson set his face strenuously. He rightly supposed, that an admiration of every kind of beauty, so far from being sinful, is essential to a complete and well-balanced mind; and the most original part of his philosophy consists of the inquiries which he made into the working and origin of our ideas on that subject. Hitherto, the Scotch had been taught that the emotions which beauty excites, were owing to the corruption of our nature, and ought to be repressed. Hutcheson, on the other hand, insisted that they were good in themselves; that they were part of the general scheme of human affairs, and that they deserved a special and scientific study.[632] And with such skill did he investigate them, that, in the opinion of one of the highest living authorities, he is the originator of all subsequent inquiries into these matters; his being the first attempt to deal with the subject of beauty in a broad and comprehensive spirit.[633]

Not only in speculative views, but also in practical recommendations, Hutcheson displayed the same tendency; every where endeavouring to break down that gloomy fabric which superstition had built up.[634] His predecessors, and, indeed, nearly all his contemporaries who exercised much influence, represented pleasure as immoral, and opposed themselves to the fine arts, which they considered dangerous, as ministering to our pleasures, and thereby distracting our minds from serious concerns. Hutcheson, however, declared that the fine arts were to be cherished; for, he said, they are not only agreeable, but also reputable, and to employ our time with them is honourable.[635] That such is the case is obvious enough to us, but it was long, indeed, since similar language had been heard in Scotland from a great public teacher, and it was completely opposed to the prevailing notions. But Hutcheson went even further. Not content with raising his voice in favour of wealth,[636] which the Scotch clergy stigmatized as one of the most pernicious and carnal of all things, he fearlessly asserted that all our natural appetites are lawful, and that the gratification of them is consistent with the highest virtue.[637] In his eyes, they were lawful, because they were natural; while, according to the theological theory, their being natural made them unlawful. And here lies the fundamental difference between the practical views of Hutcheson and those previously received. He, like every great thinker since the seventeenth century, loved human nature, and respected it; but he neither loved nor respected those who unduly trammelled it, and thereby weakened its vigour, as well as impaired its beauty. He placed more confidence in mankind, than in the rulers of mankind. The Scotch divines, who preceded him, were the libellers of their species; they calumniated the whole human race. According to them, there was nothing in us but sin and corruption; and, therefore, all our desires were to be checked. It is the peculiar glory of Hutcheson, that he was the first man in Scotland who publicly combated these degrading notions. With a noble and lofty aim did he undertake his task. Venerating the human mind, he was bent on vindicating its dignity against those who disputed its titles. Unhappily, he could not succeed; the prejudices of his time were too strong. Still, he did all that was in his power. He opposed the tide which he was unable to stem; he attacked what it was impossible to destroy; and he cast from his philosophy, with vehement scorn, those base prejudices, which, by aspersing all that is great and magnanimous, had long blinded the eyes of their contemporaries, and, by bringing into fresh prominence the old and mischievous dogma of moral degeneracy, had represented our nature as a compound of vices, and had been unable to see how many virtues we really possess, how much of the spirit of self-sacrifice, and of free disinterested benevolence has always existed; how much of good even the worst of us retain; and how, among the ordinary and average characters of whom the world is composed, the desire of benefiting others is more frequent than the desire of hurting them, kindness is more common than cruelty, and the number of good deeds does, on the whole, far outweigh the number of bad ones.[638]

Thus much as to the tendency of Hutcheson's philosophy.[639] We have now to ascertain his method, that is to say, the plan which he adopted in order to obtain his results. This is a very important part of our present inquiry; and we shall find that, in the study of moral philosophy, as in the study of all subjects not yet raised to sciences, there are not only two methods, but that each method leads to different consequences. If we proceed by induction, we arrive at one conclusion; if we proceed by deduction, we arrive at another. This difference in the results, is always a proof that the subject, in which the difference exists, is not yet capable of scientific treatment, and that some preliminary difficulties have to be removed, before it can pass from the empirical stage into the scientific one. As soon as those difficulties are got rid of, the results obtained by induction, will correspond with those obtained by deduction; supposing, of course, that both lines of argument are fairly managed. In such case, it will be of no importance whether we reason from particulars to generals, or from generals to particulars. Either plan will yield the same consequences, and this agreement between the consequences, proves that our investigation is, properly speaking, scientific. Thus, for instance, in chemistry, if, by reasoning deductively from general principles, we could always predict what would happen when we united two or more elements, even supposing those elements were new to us; and if, by reasoning inductively from each element, we could arrive at the same conclusion, one process would corroborate the other, and, by their mutual verification, the science would be complete. In chemistry, we cannot do this; therefore, chemistry is not yet a science, although, since the introduction into it, by Dalton, of the ideas of weight and number, there is every prospect of its becoming one. On the other hand, astronomy is a science, because, by employing the deductive weapon of mathematics, we can compute the motions and perturbations of bodies; and, by employing the inductive weapon of observation, the telescope reveals to us the accuracy of our previous, and, as it were, foregone, inferences. The fact agrees with the idea; the particular event confirms the general principle; the principle explains the event; and their unanimity authorizes us to believe that we must be right, since, proceed as we may, the conclusion is the same; and the inductive plan, of striking averages, harmonizes with the deductive plan, of reasoning from ideas.

But, in the study of morals there is no such harmony. Partly from the force of prejudice, and partly from the complexity of the subject, all attempts at a scientific investigation of morals have failed. It is not, therefore, surprising that, in this field, the inductive inquirer arrives at one conclusion, and the deductive inquirer at another. The inductive inquirer endeavours to attain his object by observing the actions of men, and subjecting them to analysis, in order to learn the principles which regulate them. The deductive inquirer, beginning at the other end, assumes certain principles as original, and reasons from them to the facts which actually appear in the world. The former proceeds from the concrete to the abstract; the latter, from the abstract to the concrete. The inductive moralist looks at the history of past society, or at the condition of the present, and takes for granted that the first step is, to assemble the facts, and then to generalize them. The deductive inquirer, using the facts rather to illustrate his principles, than to suggest them, appeals, in the first place, not to external facts, but to internal ideas, and he makes those ideas the major premiss of a syllogistic argument. Both parties agree, that we have the power of judging some actions to be right, and others to be wrong. But as to how we get that power, and as to what that power is, they are at utter variance. The inductive philosopher says, that its object is happiness, that we get it by association, and that it is due to the action and reaction of social causes, which are susceptible of analysis. The deductive philosopher says, that this power of distinguishing between right and wrong, aims, not at happiness, but at truth; that it is inherent, that it cannot be analyzed, that it is a primary conviction, and that we may assume it and reason from it, but can never hope to explain it by reasoning to it.

It requires but a slight acquaintance with the works of Hutcheson to see that he belongs to the latter of these two schools. He assumes, that all men have what he terms a moral faculty, which, being an original principle, does not admit of analysis.[640] He further assumes, that the business of this faculty is to regulate all our powers.[641] From these two assumptions, he reasons downwards to the visible facts of our conduct, and deductively constructs the general scheme of life. His plan being entirely synthetic, he depreciates the analytic method, and complains of it as an artful attempt to diminish the number of our perceptive powers.[642] The truth is, that every such diminution would have taken away some of his original principles, and would thereby have prevented him from using them as the major premisses of separate arguments. And if you deprive a deductive reasoner of his major premisses, you leave him nothing on which to stand. Hutcheson, therefore, like all the philosophers of his school, was extremely jealous of the invasions of the inductive spirit, with its constant tendency to attack convictions supposed to be primary, and seek to resolve them into their elements. He repulsed such encroachments upon his major premisses, because the power and beauty of his method were displayed in reasoning from the premisses, and not in reasoning to them. According to him, the moral faculty, and the authority which it exercised, were impervious to analysis; it was impossible to track them higher, or to resolve them into simpler constituents; and it was in vain that many attempted to refer them to circumstances external to themselves, such as education, custom, or the association of ideas.[643]

Hence, the judgments which men pass upon the conduct of others, or of themselves, are, in their origin, altogether inexplicable; each judgment being merely a different form of one great moral faculty. Inasmuch, however, as that faculty escapes observation, and is only known by its results, it is evident that, for all purposes of reasoning, the judgments must be deemed primary, and arguments are to be constructed from them, as if they were the ultimate and highest conditions of our nature. In this way, Hutcheson was led to that love of multiplying original principles, which Sir James Mackintosh has justly noticed as a characteristic of his philosophy, and, after him, of the Scotch philosophy in general;[644] though the distinguished author of this remark has failed to perceive that such characteristic was but a single part of a far larger scheme, and was intimately connected with those habits of deductive thought which a long train of preceding circumstances had indelibly imprinted on the Scotch mind.

In Hutcheson, the tendency was so strong, as to make him believe, that, by arguing from a certain number of original principles, he could construct the theory and explain the march of human affairs, with little or no aid from the experience of the past, or, indeed, of the present. His views, for instance, respecting the nature and objects of legislation, criminal, as well as civil, might have been written by a recluse who had never quitted his hermitage, and whose purity was still unsoiled by the realities of the world. Starting from the so-called nature of things, his first steps were ideal, and from them he sought to advance to the actual. In his account of the duties of life, as they existed before the power of government was consolidated, he quotes no evidence to show what really happened among barbarous tribes who were in that state; but he contents himself with deductive inferences from the principles he had previously laid down.[645] Difficult questions relating to the laws of property, are treated in the same manner; that is to say, the conclusions respecting them are arrived at on speculative grounds, and not by comparing how the different enactments have worked in different countries.[646] Experience is either shut out, or made subordinate to theory; and facts are adduced to illustrate the inference, but not to suggest it. So, too, the proper relation between the people and their rulers, and the amount of liberty which the people should possess, instead of being inductively generalized from an historical inquiry into the circumstances which had produced most happiness, might, in the opinion of Hutcheson, be ascertained by reasoning from the nature of government, and from the ends for which it was instituted.[647]

The next great attempt to study the actions of men scientifically, and to generalize the principles of their conduct without the intervention of supernatural ideas, was made by Adam Smith, who, in 1759, published his Theory of Moral Sentiments, and, in 1776, his Wealth of Nations. To understand the philosophy of this, by far the greatest of all the Scotch thinkers, both works must be taken together, and considered as one; since they are, in reality, the two divisions of a single subject. In the Moral Sentiments, he investigates the sympathetic part of human nature; in the Wealth of Nations, he investigates its selfish part. And as all of us are sympathetic as well as selfish; in other words, as all of us look without as well as within, and as this classification is a primary and exhaustive division of our motives to action, it is evident, that if Adam Smith had completely accomplished his vast design, he would at once have raised the study of human nature to a science, leaving nothing for subsequent inquirers except to ascertain the minor springs of affairs, all of which would find their place in this general scheme, and be deemed subordinate to it. In his attempt to perform this prodigious task, and to traverse the enormous field which he saw lying before him, he soon perceived that an inductive investigation was impossible, because it would require the labour of many lives even to assemble the materials from which the generalization was to be made. Moved by this reflection, and, probably, moved still more by the intellectual habits which prevailed around him, he resolved on adopting the deductive method instead of the inductive; but, in seeking for the premisses from which he was to reason, and on which his structure was to be built, he resorted to a peculiar artifice, which is perfectly valid, and which he had an undoubted right to employ, though, to make it available, requires such delicate tact, and involves so many refinements, that extremely few writers have used it with effect on social questions either before or since.

The plan to which I allude is, that when any subject becomes unmanageable by the inductive method, whether from the impossibility of experimenting upon it, or from its extreme natural complexity, or from the presence of immense and bewildering details collected around it, we may, in all such cases, make an imaginary separation of inseparable facts; and reason upon trains of events which have no real and independent existence, and which are nowhere to be found except in the mind of the inquirer. A result obtained in this way, cannot be strictly true; but, if we have reasoned accurately, it will be as near truth as were the premisses from which we started. To make it perfectly true, we must confront it with other results, which we have arrived at in a similar way, and from the same subject. These separate inferences may eventually be coÖrdinated into a single system; so that, while each inference contains only an imperfect truth, the whole of the inferences, when put together, will contain perfect truth.

Such hypothetical arguments are evidently based upon an intentional suppression of facts; and the artifice is necessary, because, without the suppression, the facts would be unmanageable. Each argument leads to a conclusion which approximates to truth; hence, whenever the premisses are so comprehensive as almost to exhaust the facts to which they refer, the conclusion will be so near to complete truth as to be of the greatest value, even before it is coÖrdinated with other conclusions drawn from the same department of inquiry.

Geometry exhibits the most perfect example of this logical stratagem. The object of the geometrician is, to generalize the laws of space; in other words, to ascertain the necessary and universal relations of its various parts. Inasmuch, however, as space would have no parts unless it were divided, the geometrician is forced to assume such a division; and he takes the simplest possible form of it, a division by lines. Now, a line considered as a fact, that is, as it is found in the actual world, must always have two qualities, length and breadth. However slight these qualities may be, every line has them both. But if the geometrician took both into consideration, he would find himself in the presence of a problem too complicated for the resources of the human understanding to deal with; or, at all events, too complicated for the present resources of our knowledge. He, therefore, by a scientific artifice, deliberately strikes off one of these qualities, and asserts that a line is length without breadth. He knows that the assertion is false, but he also knows that it is necessary. For, if you deny it, he can prove nothing. If you insist upon his letting into his premisses the idea of breadth, he is unable to proceed, and the whole fabric of geometry falls to the ground. Since, however, the breadth of the faintest line is so slight as to be incapable of measurement, except by an instrument used under the microscope, it follows that the assumption, that there can be lines without breadth, is so nearly true, that our senses, when unassisted by art, cannot detect the error. Formerly, and until the invention of the micrometer, in the seventeenth century, it was impossible to detect it at all. Hence, the conclusions of the geometrician approximate so close to truth, that we are justified in accepting them as true. The flaw is too minute to be perceived. But that there is a flaw, appears to me certain. It appears certain, that whenever something is kept back in the premisses, something must be wanting in the conclusion. In all such cases, the field of inquiry has not been entirely covered; and part of the preliminary facts being suppressed, it must, I think, be admitted, that complete truth is unattainable, and that no problem in geometry has yet been exhaustively solved.[648]

Still, the amazing triumphs effected in this branch of mathematics, show how powerful a weapon that form of deduction is, which proceeds by an artificial separation of facts, in themselves inseparable. So little, however, is the philosophy of the method understood, that when, late in the eighteenth century, political economy assumed a scientific form, many persons, who were otherwise well instructed, reproached its cultivators with their hard-heartedness; such objectors being unable to see, that the science could not be constructed if it were necessary to take in the whole range of generous and benevolent affections. The political economist aims at discovering the laws of wealth, which are far too complicated to be studied under every aspect. He, therefore, selects one of those aspects, and generalizes the laws as they are exhibited in the selfish parts of human nature. And he is right in doing so, simply because men, in the pursuit of wealth, consider their own gratification oftener than the gratification of others. Hence, he, like the geometrician, blots out one part of his premisses, in order that he may manipulate the remaining part with greater ease. But we must always remember, that political economy, though a profound and beautiful science, is only a science of one department of life, and is founded upon a suppression of some of the facts in which all large societies abound. It suppresses, or, what comes to the same thing, it ignores, many high and magnanimous feelings which we could ill afford to lose. We are not, therefore, to allow its conclusions to override all other conclusions. We may accept them in science, and yet reject them in practice. Thus, the political economist, when confining himself to his own department, says, with good reason, that it is both absurd and mischievous for government to undertake to supply the working-classes with employment. This assertion, he, as a political economist, can prove; and yet, notwithstanding its scientific truth, it may be practically right for a government to do the exact opposite. It may be right for a government to supply the employment, when the people are so ignorant as to demand it, and when, at the same time, they are so powerful as to plunge the country into anarchy if the demand is refused. Here, the view of the politician takes in all the premisses of which the political economist had only taken in a portion. In the same way, as a matter of economic science, it is wrong for any one to relieve the poor; since nothing is better established, than that to relieve poverty increases it, by encouraging improvidence. But, in spite of this, the antagonistic principle of sympathy will come into play, and will, in some minds, operate with such force, as to make it advisable, that he who feels it should give alms, because, if he abstains from giving them, the violence which he does to his own nature may inflict more mischief on himself, than his bestowal of charity would inflict on the general interests of society.

It will not, I hope, be considered that, in these remarks, I have digressed from the main argument of the present chapter, since, although, in making them, I have aimed at clearing up a general question respecting the nature of scientific proof, I have only done so with the more particular object of illustrating the philosophy of Adam Smith, and of explaining the method which that most profound and original thinker pursued. We shall now be able to see how entirely his plan was deductive, and what a peculiar form of deduction it was. In his two great works, he first lays down certain ideas, and from them he marches on to the facts of the external world. And, in each work, he reasons from only part of his premisses; supplying the other part in the other work. None of us are exclusively selfish, and none of us are exclusively sympathetic. But Adam Smith separates in speculation qualities which are inseparable in reality. In his Moral Sentiments, he ascribes our actions to sympathy; in his Wealth of Nations, he ascribes them to selfishness. A short view of these two works will prove the existence of this fundamental difference, and will enable us to perceive that each is supplementary to the other; so that, in order to understand either, it is necessary to study both.

In the Theory of Moral Sentiments, Adam Smith lays down one great principle from which he reasons, and to which all the others are subordinate. This principle is, that the rules which we prescribe to ourselves, and which govern our conduct, are solely arrived at by observing the conduct of others.[649] We judge ourselves, because we had previously judged them. Our notions are obtained from without, and not from within. If, therefore, we lived entirely alone, we could have no idea of merit or demerit, and it would be impossible for us to form an opinion as to whether our sentiments were right or wrong.[650] To acquire this knowledge, we must look abroad. Inasmuch, however, as we have no direct experience of what other persons actually feel, we can only gain the information by conceiving what we should feel if we were in their place.[651] Hence, all men are, in imagination, constantly changing situations with others; and though the change is ideal, and lasts but for a moment, it is the foundation of that great and universal impulse which is called Sympathy.[652]

By proceeding from these premisses, a vast number of social phenomena may be explained. We naturally sympathize with joy more than with sorrow.[653] Hence, that admiration for prosperous and successful persons, which is quite independent of any benefit we expect from them; and hence, too, the existence of different ranks and of social distinctions, all of which emanate from the same source.[654] Hence, also, the feeling of loyalty, which is a product, not of reason, nor of fear, nor of a sense of public convenience, but rather of sympathy with those above us, begetting an extraordinary compassion for even their ordinary sufferings.[655] Custom and fashion play a great part in the world, but they owe their origin entirely to sympathy;[656] and so do the various systems of philosophy which have flourished at different times, the disagreement between which depends on the fact, that each philosopher has sympathized with different ideas, some sympathizing with the notion of fitness or congruity, some with that of prudence, some with that of benevolence, and every one developing the conception paramount in his own mind.[657] To sympathy, again, we must ascribe the establishment of rewards and punishments, and the whole of our criminal laws, none of which would have existed but for our disposition to sympathize with those who either do good or suffer harm; for the circumstance of society being protected by penal laws, is a subsequent and subordinate discovery, which confirms our sense of their propriety, but did not suggest it.[658] The same principle causes the difference of character exhibited by different classes, such as the irritability of poets, compared with the coolness of mathematicians;[659] it likewise causes that social difference between the sexes, which makes men more remarkable for generosity, and women for humanity.[660] All these results illustrate the workings of sympathy, and are the remote, but still the direct, operations of that principle. Indeed, we can trace to it some of the minutest divisions of character; pride and vanity, for instance, being dependent on it, although those two passions are often confused together, and are sometimes strangely blended in the same mind.[661]

Sympathy, then, is the main-spring of human conduct. It arises, not so much from witnessing the passions of other persons, as from witnessing the situation which excites those passions.[662] To this single process we are indebted, not only for the highest principles, but also for the deepest emotions. For, the greatest affection of which we are capable, is merely sympathy fixed into habit; and the love which exists between the nearest relations, is not inherent, but is derived from this mighty and controlling principle, which governs the whole course of affairs.[663]

By this bold hypothesis, Adam Smith, at one stroke, so narrowed the field of inquiry, as to exclude from it all considerations of selfishness as a primary principle, and only to admit its great antagonist, sympathy. The existence of the antagonism, he distinctly recognizes. For, he will not allow that sympathy is in any way to be deemed a selfish principle.[664] Although he knew that it is pleasurable, and that all pleasure contains an element of selfishness, it did not suit the method of his philosophy to subject the principle of sympathy to such an inductive analysis as would reveal its elements. His business was, to reason from it, and not to it. Concentrating his energy upon the deductive process, and displaying that dialectic skill which is natural to his countrymen, and of which he himself was one of the most consummate masters the world has ever seen, he constructed a system of philosophy, imperfect indeed, because the premisses were imperfect, but approaching truth as closely as it was possible for any one to do who abstained from giving due consideration to the selfish part of human nature. Into the workings of its sympathetic part, he looked with a minuteness, and he reasoned from it with a subtlety, which make his work the most important that has ever been written on this interesting subject. But, inasmuch as his plan involved a deliberate suppression of preliminary and essential facts, the results which he obtained do not strictly correspond to those which are actually observed in the world.[665] This, however, as I have shown, is not a valid objection; since such discrepancy between the ideal and the actual, or between the abstract and the concrete, is the necessary consequence of that still early condition of our knowledge, which forces us to study complicated questions piecemeal, and to raise them to sciences by separate and fragmentary investigations.

That Adam Smith saw this necessity, and that his seeing it was the cause of the method he pursued, is evident from the fact, that in his next great work he followed the same plan, and, though he argued from new premisses, he carefully avoided arguing from any of the old ones. Convinced that, in his theory of morals, he had reasoned as accurately as possible from the principles supplied by sympathy, his capacious and insatiable mind, deeming that nothing had been done while aught remained to do, urged him to pass on to the opposite passion of selfishness, and treat it in the same manner, so that the whole domain of thought might be covered. This he did in his Wealth of Nations, which, though even a greater work than his Moral Sentiments, is equally one-sided, in reference to the principles which it assumes. It assumes that selfishness is the main regulator of human affairs, just as his previous work had assumed sympathy to be so. Between the two works there elapsed an interval of seventeen years; the Wealth of Nations not being published till 1776. But what shows that to their author both were part of a single scheme, is the notable circumstance, that, so early as 1753, he had laid down the principles which his later work contains.[666] This was while his former work was still in meditation, and before it had seen the light. It is, therefore, clear, that the study which he made, first of one passion, and then of its opposite, was not a capricious or accidental arrangement, but was the consequence of that vast idea which presided over all his labours, and which, when they are rightly understood, gives to them a magnificent unity. And a glorious object of ambition it was. His aspiring and comprehensive genius, sweeping the distant horizon, and taking in the intermediate space at a glance, sought to traverse the whole ground in two separate and independent directions, indulging the hope, that, by supplying in one line of argument the premisses which were wanting in the other, their opposite conclusions would be compensatory rather than hostile, and would serve as a broad and permanent basis on which one great science of human nature might be safely built.

The Wealth of Nations is, as I have elsewhere observed,[667] probably the most important book which has ever been written, whether we consider the amount of original thought which it contains, or its practical influence. Its practical recommendations were extremely favourable to those doctrines of freedom which the eighteenth century ushered in; and this secured to them an attention which otherwise they would not have received. While, therefore, the Wealth of Nations was the proximate cause of a great change in legislation,[668] a deeper analysis will show, that the success of the book, and, consequently, the alteration of the laws, depended upon the operation of more remote and general causes. It must also be confessed, that those same causes predisposed the mind of Adam Smith to the doctrines of liberty, and gave him a sort of prejudice in favour of conclusions which limited the interference of the legislator. Thus much he borrowed from his age; but one thing he did not borrow. His wide and organizing mind was all his own. This would have made him great under any circumstances; to make him powerful, required a peculiar conjunction of events. That conjunction he enjoyed, and he turned it to good account. The influence of his contemporaries was enough to make him liberal; his own capacity was enough to make him comprehensive. He had, in a most remarkable degree, that exuberance of thought, which is one of the highest forms of genius, but which leads those who possess it into distant excursions, which, though they have one common aim, are often stigmatized as digressions, simply because they who criticize are unable to discern the great principle which pervades the whole, and unites the various parts into a single scheme. This has been especially the case with Adam Smith, whose immortal work has often been exposed to such shallow objections. And certainly, the Wealth of Nations displays a breadth of treatment which those who cannot sympathize with, are very likely to ridicule. The phenomena, not only of wealth, but also of society in general, classified and arranged under their various forms; the origin of the division of labour, and the consequences which that division has produced; the circumstances which gave rise to the invention of money, and to the subsequent changes in its value; the history of those changes traced in different ages, and the history of the relations which the precious metals bear to each other; an examination of the connection between wages and profits, and of the laws which govern the rise and fall of both; another examination of the way in which these are concerned, on the one hand, with the rent of land, and, on the other hand, with the price of commodities; an inquiry into the reason why profits vary in different trades, and at different times; a succinct, but comprehensive, view of the progress of towns in Europe since the fall of the Roman Empire; the fluctuations, during several centuries, in the prices of the food of the people, and a statement of how it is, that, in different stages of society, the relative cost of land and of meat varies; the history of corporation laws and of municipal enactments, and their bearing on the four great classes of apprentices, manufacturers, merchants, and landlords; an account of the immense power and riches formerly enjoyed by the clergy, and of the manner in which, as society advances, they gradually lose their exclusive privileges; the nature of religious dissent, and the reason why the clergy of the established Church can never contend with it on terms of equality, and, therefore, call on the State to help them, and wish to persecute when they cannot persuade; why some sects profess more ascetic principles, and others more luxurious ones; how it was, that, during the feudal times, the nobles acquired their power, and how that power has, ever since, been gradually diminishing; how the rights of territorial jurisdiction originated, and how they died away; how the sovereigns of Europe obtained their revenue, what the sources of it are, and what classes are most heavily taxed in order to supply it; the cause of certain virtues, such as hospitality, flourishing in barbarous ages, and decaying in civilized ones; the influence of inventions and discoveries in altering the distribution of power among the various classes of society; a bold and masterly sketch of the peculiar sort of advantages which Europe derived from the discovery of America and of the passage round the Cape; the origin of universities, their degeneracy from their original plan, the corruption which has gradually crept over them, and the reason why they are so unwilling to adopt improvements, and to keep pace with the wants of the age; a comparison between public and private education, and an estimate of their relative advantages;—these, and a vast number of other subjects, respecting the structure and development of society, such as the feudal system, slavery, emancipation of serfs, origin of standing armies, and of mercenary troops, effects produced by tithes, laws of primogeniture, sumptuary laws, international treaties concerning trade, rise of European banks, national debts, influence of dramatic representations over opinions, influence of foreign travels over opinions, colonies, poor-laws,—all topics of a miscellaneous character, and many of them diverging from each other,—all are fused into one great system, and irradiated by the splendour of one great genius. Into that dense and disorderly mass, did Adam Smith introduce symmetry, method, and law. At his touch, anarchy disappeared, and darkness was succeeded by light. Much, of course, he took from his predecessors, though nothing like so much as is commonly supposed. On this sort of borrowing, the best and strongest of us are dependent. But, after making every possible allowance for what he gathered from others, we must honestly say, that no single man ever took so great a step upon so important a subject, and that no single work which is now preserved, contains so many views, which were novel at the time, but which subsequent experience has ratified. What, however, for our present purpose, is most important to observe, is, that he obtained these results by arguing from principles which the selfish part of human nature exclusively supplied, and that he omitted those sympathetic feelings of which every human being possesses at least some share, but which he could not take into consideration, without producing a problem, the number of whose complications it would have been hopeless to unravel.

To avoid, therefore, being baffled, he simplified the problem, by erasing from his view of human nature those premisses which he had already handled in his Theory of Moral Sentiments. At the beginning of the Wealth of Nations, he lays down two propositions: 1st, that all wealth is derived, not from land, but from labour; and 2d, that the amount of the wealth depends, partly on the skill with which the labour is conducted, and partly on the proportion between the number of those who labour and the number of those who do not labour. The rest of the work, is an application of these principles, to explain the growth and mechanism of society. In applying them, he everywhere assumes, that the great moving power of all men, all interests, and all classes, in all ages, and in all countries, is selfishness. The opposite power of sympathy he entirely shuts out; and I hardly remember an instance in which even the word occurs in the whole course of his work. Its fundamental assumption is, that each man exclusively follows his own interest, or what he deems to be his own interest. And one of the peculiar features of his book is, to show that, considering society as a whole, it nearly always happens that men, in promoting their own interest, will unintentionally promote the interest of others. Hence, the great practical lesson is, not to restrain selfishness, but to enlighten it; because there is a provision in the nature of things, by which the selfishness of the individual accelerates the progress of the community. According to this view, the prosperity of a country depends on the amount of its capital; the amount of its capital depends on the habit of saving, that is, on parsimony, as opposed to generosity; while the habit of saving is, in its turn, governed by the desire we all feel of bettering our condition,—a desire so inherent in our nature, that it comes with us from the womb, and only leaves us in the grave.[669]

This constant effort of every man, to better his own condition, is so salutary, as well as so powerful, that it is often capable of securing the progress of society, in spite of the folly and extravagance of the rulers of mankind.[670] If it were not for this propensity, improvement would be impossible. For human institutions are constantly stopping our advance, by thwarting our natural inclinations.[671] And no wonder that this should be the case, seeing that the men who are at the head of affairs, and by whom the institutions are contrived, have, perhaps, a certain rough and practical sagacity; but being, from the narrowness of their understandings, incapable of large views, their councils are determined by those mere casual fluctuations which alone they are able to perceive.[672] They do not see that we have prospered, not on account of their enactments, but in the teeth of them; and that the real cause of our prosperity is the fact that we enjoy undisturbed the fruit of our own labour.[673] Whenever this right is tolerably secure, every man will be bent on procuring for himself either present enjoyment or future profit; and if he does not aim at one of these objects, he is void of common understanding.[674] If he possess capital, he will probably aim at both, but, in doing so, he will never consider the interest of others; his sole motive will be his own private profit.[675] And it is well that such should be the case. For, by thus pursuing his personal interest, he aids society more than if his views were generous and exalted. Some people affect to carry on trade for the good of others; but this is mere affectation, though, to say the truth, it is an affectation not very common among merchants, and many words are not needed to dissuade them from so foolish a practice.[676]

In this way, Adam Smith completely changes the premisses which he had assumed in his earlier work. Here, he makes men naturally selfish; formerly, he had made them naturally sympathetic.[677] Here, he represents them as pursuing wealth for sordid objects, and for the narrowest personal pleasures; formerly he represented them as pursuing it out of regard to the sentiments of others, and for the sake of obtaining their sympathy.[678] In the Wealth of Nations, we hear no more of this conciliatory and sympathetic spirit; such amiable maxims are altogether forgotten, and the affairs of the world are regulated by different principles. It now appears that benevolence and affection have no influence over our actions. Indeed, Adam Smith will hardly admit common humanity into his theory of motives. If a people emancipate their slaves, it is a proof, not that the people are acted on by high moral considerations, nor that their sympathy is excited by the cruelty inflicted on these unhappy creatures. Nothing of the sort. Such inducements to conduct are imaginary, and exercise no real sway. All that the emancipation proves, is, that the slaves were few in number, and, therefore, small in value. Otherwise, they would not have been emancipated.[679]

So, too, while in his former work, he had ascribed the different systems of morals to the power of sympathy, he, in this work, ascribes them entirely to the power of selfishness. He observes, that, among the lower ranks of society, dissipation is more fatal to individuals, than it is among the higher ranks. The extravagance which dissipation produces, may injure the fortune of a wealthy man, but the injury is usually capable of being repaired, or, at all events, he can indulge his vices for years without completely destroying his fortune, and without bringing himself to utter ruin. To the labourer, a similar indulgence would be fatal in a single week; it would not merely reduce him to beggary, and perhaps send him to jail, but it would destroy his future prospects, by taking away that character for sobriety and regularity on which his employment depends. Hence, the better class of common people, guided by their interest, look with aversion on excesses which they know to be fatal; while the upper ranks finding that a moderate amount of vice hurts neither their purse nor their reputation consider such license to be one of the advantages which their fortune confers, and they value, as one of the privileges belonging to their station, the liberty of indulging themselves without being censured. Therefore it is, that they who dissent from the established Church have a purer system of morals, or, at all events, an austerer one, than they who agree with it. For, new religious sects usually begin among the common people, the thinking part of whom are, by their interest, driven to strict views of the duties of life. Consequently, the advocates of the new opinion profess a similar strictness, seeing that it is the surest means of increasing their proselytes. Thus it is that sectaries and heretics, governed by interest rather than by principle, adopt a code of morals which is suited to their own purpose, and the rigidity of which is strongly contrasted with the laxer code of more orthodox believers.[680] Owing to the operation of the same principle, we also find, that, among the orthodox themselves, the clergy embrace a stricter system of morals in countries where church benefices are nearly equal than they do in countries where the benefices are very unequal. This is because, when all the benefices are nearly equal, none can be very rich, and, consequently, even the most conspicuous among the clergy will have but small incomes. But a man who has little to spend can have no influence, unless his morals are exemplary. Having no wealth to give him weight the vices of levity would make him ridiculous. To avoid contempt, and also to avoid the expense which a looseness of conduct occasions, and which his narrow circumstances cannot afford, he has but one remedy, and that remedy he adopts. He retains his influence, and saves his pocket, by protesting against pleasures which he cannot conveniently enjoy; in this, as in all other cases, pursuing that plan of life which his own interest urges him to follow.[681]

In these striking generalizations, which, though they contain a large amount of truth, are far from containing the whole truth, no room is left for the magnanimous parts of our nature to act; but the system of morals, prevailing at any one time or in any one class, is solely ascribed to the dictates of unalloyed selfishness. Adam Smith, by reasoning from this principle, with that exquisite subtlety which characterized his mind, explains many other circumstances which society presents, and which at first sight appear incongruous. According to the old notions, which, indeed, are not yet quite extinct, those who received wages were under a personal obligation to those who paid them; that is to say, they were under a moral obligation, over and above the obligation of performing certain services. It was believed that a master could not only select what servants he chose, but could pay them what he chose; or, at all events, that it was the will of the masters, considered as a body, which fixed the usual and average rate of wages.[682] The lower classes were, therefore, much indebted to the higher ones for giving them so much as they did; and it was incumbent upon all persons, who received wages, to take them with humble thankfulness, and with a feeling of gratitude, on account of the favour bestowed upon them by the generosity of their superiors.

This doctrine, so convenient to the upper classes of society, and so natural to the universal ignorance which formerly prevailed on these matters, began to be shaken by the speculative thinkers of the seventeenth century; but it was reserved for the eighteenth century to overthrow it, by letting in the great idea of necessity, and proving, that the rate of wages established in a country, was the inevitable consequence of the circumstances in which that country was placed, and had no connexion with the wishes of any individual, or, indeed, with the wishes of any class. To all instructed persons, this is now a familiar truth. Its discovery has excluded the notion of gratitude from the pecuniary relation between employers and employed, and has made known that servants or workmen who receive wages, have no more reason to be grateful than those who pay them. For, no choice having been exercised in fixing the wages, no favour can be conferred in their payment. The whole process is compulsory, and is the result of what had previously happened. Scarcely had the eighteenth century passed away, when this most important discovery was completed. It was decisively proved, that the reward of labour depends solely on two things; namely, the magnitude of that national fund out of which all labour is paid, and the number of the labourers among whom the fund is to be divided.

This vast step in our knowledge is due, mainly, though not entirely, to Malthus, whose work on Population, besides marking an epoch in the history of speculative thought, has already produced considerable practical results, and will probably give rise to others more considerable still. It was published in 1798; so that Adam Smith, who died in 1790, missed what to him would have been the intense pleasure of seeing how, in it, his own views were expanded rather than corrected. Indeed, it is certain, that without Smith there would have been no Malthus; that is, unless Smith had laid the foundation, Malthus could not have raised the superstructure. It was Adam Smith, who, far more than any other man, introduced the conception of uniform and necessary sequence into the apparently capricious phenomena of wealth, and who studied those phenomena by the aid of principles, of which selfishness alone supplied the data. According to his view, the employers of labour have, as employers, no benevolence, no sympathy, no virtue of any kind. Their sole aim is, their own selfish interest. They are constantly engaged in a tacit, if not in an open, combination, to prevent the lower ranks from being benefited by a rise of wages; and they sometimes combine for the purpose even of depressing those wages below their actual rate.[683] Having no bowels, they think only of themselves. The idea of their wishing to mitigate the inequalities of fortune, is to be exploded as one of the chimeras of that protective spirit, which imagined that society could not go on, unless the richer classes relieved the poorer ones, and sympathized with their troubles. This antiquated notion is further rebutted by the fact, that wages are always higher in summer than in winter, although the expenses which a labourer incurs in winter, being heavier than in summer, he ought, on principles of common humanity, to receive more money during the more expensive season.[684] In the same way, in years of scarcity, the dearness of food causes many persons to go to service, in order to support their families. The masters, instead of charitably paying such servants more on account of the unfortunate position in which they are placed, avail themselves of that position to pay them less. They make better terms for themselves; they lower wages just at the moment when sympathy for misfortune would have raised them; and, as they find that their servants, besides being worse remunerated, are, by poverty, made more submissive, they consider that scarcity is a blessing, and that dear years are to be commended as more favourable to industry than cheap ones.[685]

Adam Smith, therefore, though he failed in grasping the remote cause of the rate of wages, clearly saw that the approximate cause was, not the generosity of human nature, but its selfishness, and that the question was one of supply and demand; each side striving to extract as much as possible from the other.[686] By the aid of the same principle, he explained another curious fact, namely, the extravagant rewards bestowed on some of the most despicable classes of society, such, for instance, as opera-dancers, who always receive enormous pay for insignificant services. He observes, that one of the reasons why we pay them so highly, is, because we despise them. If to be a public dancer were a creditable occupation, more persons would be brought up to it, and the supply of public dancers becoming greater, competition would lower their wages. As it is, we look on them disdainfully. By way of compensating the disdain, we have to bribe them largely to induce them to follow their pursuit.[687] Here we see, that the reward which one class bestows on another, instead of being increased by sympathy, is increased by scorn; so that the more we contemn the tastes and the way of life of our fellow-creatures, the more liberal we are in recompensing them.

Passing to another, and somewhat different, class, Adam Smith threw new light on the cause of that hospitality for which the clergy were famous during the Middle Ages, and for the magnificence of which they have received great praise. He shows that, although they undoubtedly relieved a large amount of distress, this is not to be ascribed to them as a merit, since it resulted from the peculiarity of their position, and since, moreover, they did it for their own advantage. In the Middle Ages, the clergy possessed enormous wealth, and their revenues were mostly paid, not in money, but in kind, such as corn, wine, and cattle. Trade and manufactures being hardly known, the clergy could find no use for these commodities except to feed other people. By employing them in that way, they benefited themselves in the most effectual manner. They gained a reputation for extensive charity; they increased their influence; they multiplied the number of their adherents; and they not only advanced themselves to temporal power, but they secured to their spiritual threats a respect, which, without this contrivance, it would have been impossible for them to obtain.[688]

The reader will now be able to understand the nature of that method of investigation which is adopted in the Wealth of Nations, and of which I have given more instances than I should otherwise have done, partly because the question of philosophic method lies at the very root of our knowledge, and partly because no attempt has hitherto been made to analyze the intellect of Adam Smith, by considering his two great works as the opposite, but yet the compensatory, parts of a single scheme. And, as he is by far the greatest thinker Scotland has produced, I need hardly apologize, in a history of the Scotch mind, for devoting so much attention to his system, and endeavouring to examine it at its base. But, having done so, it would be a needless prolixity to treat with equal fulness the productions of those other eminent Scotchmen who lived at the same time, and nearly all of whom pursued a method essentially, though not entirely, the same; that is to say, they preferred the deductive process of reasoning from principles, to the inductive process of reasoning to them. In that peculiar form of deduction which consists in a deliberate suppression of part of the principles, Adam Smith stands alone. For, though others attempted to follow that plan, they did so irregularly, and at intervals, and did not, like him, see the importance of keeping close to their method, and of invariably abstaining from letting into the premisses of their arguments, considerations which would complicate the problem that they wished to solve.

Among the contemporaries of Adam Smith, one of the first, in eminence, as well as in reputation, is David Hume. His views respecting political economy were published in 1752,[689] that is, the very year in which Adam Smith taught the principles subsequently unfolded in the Wealth of Nations. But Hume, though a most accomplished reasoner, as well as a profound and fearless thinker, had not the comprehensiveness of Adam Smith, nor had he that invaluable quality of imagination without which no one can so transport himself into past ages as to realize the long and progressive movements of society, always fluctuating, yet, on the whole, steadily advancing. How unimaginative he was, appears, not only from the sentiments he expressed, but likewise from many traits in his private life.[690] It appears, also, in the very colour and mechanism of his language; that beautiful and chiselled style in which he habitually wrote, polished as marble, but cold as marble too, and wanting that fiery enthusiasm and those bursts of tempestuous eloquence, which, ever and anon, great objects naturally inspire, and which rouse men to their inmost depths. This it was, which, in his History of England,—that exquisite production of art, which, in spite of its errors, will be admired as long as taste remains among us,—prevented him from sympathizing with those bold and generous natures, who, in the seventeenth century, risked their all to preserve the liberty of their country. His imagination was not strong enough to picture the whole of that great century, with its vast discoveries, its longings after the unknown, its splendid literature, and what was better than all these, its stern determination to vindicate freedom, and to put down tyranny. His clear and powerful understanding saw these things separately, and in their various parts, but could not fuse them into a single form, because he lacked that peculiar faculty which assimilates the past to the present, and enables the mind to discern both with almost equal ease. That Great Rebellion, which he ascribed to the spirit of faction, and the leaders of which he turned into ridicule, was but the continuation of a movement which can be clearly traced to the twelfth century, and of which such events as the invention of printing, and the establishment of the Reformation, were merely successive symptoms. For all this, Hume cared nothing. In regard to philosophy, and in regard to the purely speculative parts of religious doctrines, his penetrating genius enabled him to perceive that nothing could be done, except by a spirit of fearless and unrestrained liberty. But this was the liberty of his own class; the liberty of thinkers, and not of actors. His absence of imagination prevented him from extending the range of his sympathy beyond the intellectual classes, that is, beyond the classes of whose feelings he was directly cognizant. It would, therefore, appear, that his political errors were due, not, as is commonly said, to his want of research, but rather to the coldness of his temperament.[691] It was this which made him stop where he did, and which gave to his works the singular appearance of a profound and original thinker, in the middle of the eighteenth century, advocating practical doctrines, so illiberal, that, if enforced, they would lead to despotism, and yet, at the same time, advocating speculative doctrines, so fearless and enlightened, that they were not only far in advance of his own age, but have, in some degree, outstripped even the age in which we live.

Among his speculative views, the most important are his theory of causation as discarding the idea of power, and his theory of the laws of association. Neither of these theories are, in their primary conception, quite original, but his treatment made them as valuable as if they had been entirely his own. His theory of miracles, in connexion, on the one hand, with the principles of evidence, and, on the other hand, with the laws of causation, is worked out with consummate skill, and, after having received the modifications subsequently imposed by Brown, has now become the foundation on which the best inquirers into these matters take their stand.[692] His work on the principles of morals, by generalizing the laws of expediency, prepared the way for Bentham, who afterwards incorporated with them an estimate of the more remote consequences of human actions; Hume, having chiefly confined himself to their more immediate consequences. The doctrine of utility was common to each; but while Hume applied it mainly to the individual, Bentham applied it to the surrounding society. Though Bentham was more comprehensive, yet Hume, having come first, was more original. The praise of originality must also be accorded to his economical theories, in which he advocated those principles of free trade, which politicians began to adopt many years after his death.[693] In opposition to the notions then prevailing, he distinctly asserted, that all commodities, though apparently bought by money, are in reality bought by labour.[694] Money, therefore, is not the subject of commerce, and is of no use except to facilitate it.[695] Hence, it is absurd for a nation to trouble itself about the balance of trade, or to make regulations to discourage the exportation of the precious metals.[696] Neither does the average rate of interest depend on their scarcity or abundance, but upon the operation of more general causes.[697] As a necessary consequence of these positions, Hume inferred that the established policy was wrong, which made trading states look upon each other as rivals, while, in point of fact, the question, if considered from a certain height, was one, not of rivalry, but of coÖperation; every country being benefited by the increasing wealth of its neighbours.[698] Those who know the character of commercial legislation, and the opinions of even the most enlightened statesmen a century ago, will consider these views as extremely remarkable to have been propounded in the year 1752. But what is more remarkable still, is, that their author subsequently detected the fundamental error which Adam Smith committed, and which vitiates many of his conclusions. The error consists in his having resolved price into three components, namely, wages, profit, and rent; whereas it is now known that price is a compound of wages and profit, and that rent is not an element of it, but a result of it. This discovery is the corner-stone of political economy; but it is established by an argument so long and so refined, that most minds are unable to pursue it without stumbling, and the majority of those who acquiesce in it are influenced by the great writers to whom they pay deference, and whose judgment they follow. It is, therefore, a striking proof of the sagacity of Hume, that in an age when the science was but dawning, and when he could receive little help from his predecessors, he should have discovered a mistake of this sort, which lies so far beneath the surface. Directly the Wealth of Nations appeared, he wrote to Adam Smith, disputing his position that rent is a part of price;[699] and this letter, written in the year 1776, is the first indication of that celebrated theory of rent, which, a little later, Anderson, Malthus, and West, saw, and imperfectly developed, but which it was reserved for the genius of Ricardo to build up on a broad and solid foundation.

It is very observable, that Hume and Adam Smith, who made such immense additions to our knowledge of the principles of trade, had no practical acquaintance with it.[700] Hume had, at an early period of his life, been in a mercantile house; but he threw up that employment in disgust, and buried himself in a provincial town, to think, rather than to observe.[701] Indeed, one of the capital defects of his mind, was a disregard of facts. This did not proceed, as is too often the case, from that worst form of moral obliquity, an indifference to truth; since he, on the contrary, was an ardent lover of it, and was, moreover, a man of the purest and most exemplary character, utterly incapable of falsehood, or of prevarication of any kind.[702] In him, a contempt for facts was merely the exaggerated result of a devotion to ideas. He not only believed, with perfect justice, that ideas are more important than facts, but he supposed that they should hold the first place in the order of study, and that they should be developed before the facts are investigated. The Baconian philosophy, which, though it allows a preliminary and tentative hypothesis, strongly insists upon the necessity of first collecting the facts, and then proceeding to the ideas, excited his aversion; and this, I have no doubt, is the reason why he, who was usually so lenient in his judgments, and was so keen an admirer of intellectual greatness is, nevertheless, grossly unfair towards Bacon, with whose method it was impossible for him to sympathize, though he could not deny its utility, in physical science.[703] If Hume had followed the Baconian scheme, of always rising from particulars to generals, and from each generalization to that immediately above it, he would hardly have written one of his works. Certainly, his economical views would never have appeared, since political economy is as essentially a deductive science as geometry itself.[704] Reversing the inductive process, he was in favour of beginning with what he termed general arguments, by which he hoped to demonstrate the inaccuracy of opinions which facts were supposed to have proved.[705] He did not stop to investigate the facts from which the inference had been drawn, but he inverted the order by which the inference was to be obtained. The same dislike to make the facts of trade the basis of the science of trade, was displayed by Adam Smith, who expresses his want of confidence in statistics, or, as it was then termed, political arithmetic.[706] It is, however, evident, that statistical facts are as good as any other facts, and, owing to their mathematical form, are very precise.[707] But when they concern human actions, they are the result of all the motives which govern those actions; in other words, they are the result, not merely of selfishness, but also of sympathy. And as Adam Smith, in the Wealth of Nations, dealt with only one of these passions, namely, selfishness, he would have found it impossible to conduct his generalization from statistics, which are necessarily collected from the products of both passions. Such statistical facts were, in their origin, too complex to be generalized; especially as they could not be experimented upon, but could only be observed and arranged. Adam Smith, perceiving them to be unmanageable, very properly rejected them as the basis of his science, and merely used them by way of illustration, when he could select what he liked. The same remark applies to other facts which he drew from the history of trade, and, indeed, from the general history of society. All of these are essentially subsequent to the argument. They make the argument more clear, but not more certain. For, it is no exaggeration to say, that, if all the commercial and historical facts in the Wealth of Nations were false, the book would still remain, and its conclusions would hold equally good, though they would be less attractive. In it, every thing depends upon general principles, and they, as we have seen, were arrived at in 1752, that is, twenty-four years before the work was published in which those principles were applied. They must, therefore, have been acquired independently of the facts which Adam Smith, subsequently incorporated with them, and which he learnt during that long period of twenty-four years. And the ten years which he employed in composing his great work, were not spent in one of those busy haunts of men, where he might have observed all the phenomena of industry, and studied the way in which the operations of trade affect human character, and are affected by it. He did not resort to one of those vast marts and emporiums of commerce, where the events were happening which he was seeking to explain. That was not his method. On the contrary, the ten years, during which he was occupied in raising to a science the most active department of life, were passed in complete seclusion in Kirkaldy, his quiet little birthplace.[708] He had always been remarkable for absence of mind, and was so little given to observation, as to be frequently oblivious of what was passing around him.[709] In that obliviousness, he, amid the tranquil scenes of his childhood, could now indulge without danger. There, cheered, indeed, by the society of his mother, but with no opportunity of observing human nature upon a large scale, and far removed from the hum of great cities, did this mighty thinker, by the force of his own mind, unravel the numerous and complicated phenomena of wealth, detect the motives which regulate the conduct of the most energetic and industrious portion of mankind, and lay bare the schemes and the secrets of that active life from which he was shut out, while he, immured in comparative solitude, was unable to witness the very facts which he succeeded in explaining.

The same determination to make the study of principles precede that of facts, is exhibited by Hume in one of his most original works, the Natural History of Religion. In reference to the title of this treatise, we must observe that, according to the Scotch philosophers, the natural course of any movement is by no means the same as its actual course. This discrepancy between the ideal and the real, was the unavoidable result of their method.[710] For, as they argued deductively from fixed premisses, they could not take into account the perturbations to which their conclusions were liable, from the play and friction of the surrounding society. To do that, required a separate inquiry. It would have been needful to investigate the circumstances which caused the friction, and thus prevented the conclusions from being, in the world of fact, the same as they were in the world of speculation. What we call accidents, are constantly happening, and they prevent the real march of affairs from being identical with the natural march. And, as long as we are unable to predict those accidents, there will always be a want of complete harmony between the inferences of a deductive science and the realities of life; in other words, our inferences will tend towards truth, but never completely attain it.[711]

With peculiar propriety, therefore, did Hume term his work a Natural History of Religion. It is an admirable specimen of the deductive method. Its only fault is that he speaks too confidently of the accuracy of the results to which, on such a subject, that method could attain. He believed, that, by observing the principles of human nature, as he found them in his own mind, it was possible to explain the whole course of affairs, both moral and physical.[712] These principles were to be arrived at by experiments made on himself; and having thus arrived at them, he was to reason from them deductively, and so construct the entire scheme. This he contrasts with the inductive plan, which he calls a tedious and lingering process; and while others might follow that slow and patient method of gradually working their way towards first principles, his project was, to seize them at once, or, as he expresses himself, not to stop at the frontier, but to march directly on the capital, being possessed of which, he could gain an easy victory over other difficulties, and could extend his conquests over the sciences.[713] According to Hume, we are to reason, not in order to obtain ideas, but we are to have clear ideas before we reason.[714] By this means, we arrive at philosophy; and her conclusions are not to be impugned, even if they do happen to clash with science. On the contrary, her authority is supreme, and her decisions, being essentially true, must always be preferred to any generalization of the facts which the external world presents.[715]

Hume, therefore, believed that all the secrets of the external world are wrapped up in the human mind. The mind was not only the key by which the treasure could be unlocked; it was also the treasure itself. Learning and science might illustrate and beautify our mental acquisitions, but they could not communicate real knowledge; they could neither give the prime original materials, nor could they teach the design according to which those materials must be worked.

In conformity with these views, the Natural History of Religion was composed. The object of Hume in writing it, was, to ascertain the origin and progress of religious ideas; and he arrives at the conclusion, that the worship of many Gods must, every where, have preceded the worship of one God. This, he regards as a law of the human mind, a thing not only that always has happened, but that always must happen. His proof is entirely speculative. He argues that the earliest state of man is necessarily a savage state; that savages can feel no interest in the ordinary operations of nature, and no desire to study the principles which govern those operations; that such men must be devoid of curiosity on all subjects which do not personally trouble them; and that, therefore, while they neglect the usual events of nature, they will turn their minds to the unusual ones.[716] A violent tempest, a monstrous birth, excessive cold, excessive rain, sudden and fatal diseases, are the sort of things to which the attention of the savage is confined, and of which alone he desires to know the causes. Directly he finds that such causes are beyond his control, he reckons them superior to himself, and, being incapable of abstracting them, he personifies them; he turns them into deities; polytheism is established; and the earliest creed of mankind assumes a form which can never be altered, as long as men remain in this condition of pristine ignorance.[717]

These propositions, which are not only plausible, but which are probably true, ought, according to the inductive philosophy, to have been generalized from a survey of facts; that is, from a collection of evidence respecting the state of religion and of the speculative faculties among savage tribes. But this, Hume abstains from doing. He refers to none of the numerous travellers who have visited such people; he does not, in the whole course of his work, mention even a single book where facts respecting savage life are preserved. It was enough for him, that the progress from a belief in many Gods to a belief in one God, was the natural progress; which is saying, in other words, that it appeared to his mind to be the natural progress.[718] With that, he was satisfied. In other parts of his essay, where he treats of the religious opinions of the ancient Greeks and Romans, he displays a tolerable, though by no means remarkable, learning; but the passages which he cites, do not refer to that entirely barbarous society in which, as he supposes, polytheism first arose. The premisses, therefore, of the argument are evolved out of his own mind. He reasons deductively from the ideas which his powerful intellect supplied, instead of reasoning inductively from the facts which were peculiar to the subject he was investigating.

Even in the rest of his work, which is full of refined and curious speculation, he uses facts, not to demonstrate his conclusions, but to illustrate them. He, therefore, selected those facts which suited his purpose, leaving the others untouched. And this, which many critics would call unfair, was not unfair in him; because he believed, that he had already established his principles without the aid of those facts. The facts might benefit the reader, by making the argument clearer, but they could not strengthen the argument. They were more intended to persuade than to prove; they were rather rhetorical than logical. Hence, a critic would waste his time if he were to sift them with a minuteness which would be necessary, supposing that Hume had built an inductive argument upon them. Otherwise, without going far, it might be curious to contrast them with the entirely different facts which Cudworth, eighty years before, had collected from the same source, and on the same subject. Cudworth, who was much superior to Hume in learning, and much inferior to him in genius,[719] displayed, in his great work on the Intellectual System of the Universe, a prodigious erudition, to prove that, in the ancient world, the belief in one God was a prevailing doctrine. Hume, who never refers to Cudworth, arrives at a precisely opposite conclusion. Both quoted ancient writers; but while Cudworth drew his inferences from what he found in those writers, Hume drew his from what he found in his own mind. Cudworth, being more learned, relied on his reading; Hume, having more genius, relied on his intellect. Cudworth, trained in the school of Bacon, first collected the evidence, and then passed the judgment. Hume, formed in a school entirely different, believed that the acuteness of the judge was more important than the quantity of the evidence; that witnesses were likely to prevaricate; and that he possessed, in his own mind, the surest materials for arriving at an accurate conclusion. It is not, therefore, strange, that Cudworth and Hume, pursuing opposite methods, should have obtained opposite results, since such a discrepancy is, as I have already pointed out, unavoidable, when men investigate, according to different plans, a subject which, in the existing state of knowledge, is not amenable to scientific treatment.

The length to which this chapter has already extended, and the number of topics which I have still to handle, will prevent me from examining, in detail, the philosophy of Reid, who was the most eminent among the purely speculative thinkers of Scotland, after Hume and Adam Smith, though, in point of merit, he must be placed far below them. For, he had neither the comprehensiveness of Smith, nor the fearlessness of Hume. The range of his knowledge was not wide enough to allow him to be comprehensive; while a timidity, almost amounting to moral cowardice, made him recoil from the views advocated by Hume, not so much on account of their being false, as on account of their being dangerous. It is, however, certain, that no man can take high rank as a philosopher, who allows himself to be trammelled by considerations of that kind. A philosopher should aim solely at truth, and should refuse to estimate the practical tendency of his speculations. If they are true, let them stand; if they are false, let them fall. But, whether they are agreeable or disagreeable, whether they are consolatory or disheartening, whether they are safe or mischievous, is a question, not for philosophers, but for practical men. Every new truth which has ever been propounded, has, for a time, caused mischief; it has produced discomfort, and often unhappiness, sometimes by disturbing social or religious arrangements, and sometimes merely by the disruption of old and cherished associations of thought. It is only after a certain interval, and when the framework of affairs has adjusted itself to the new truth, that its good effects preponderate; and the preponderance continues to increase, until, at length, the truth causes nothing but good. But, at the outset, there is always harm. And, if the truth is very great, as well as very new, the harm is serious. Men are made uneasy; they flinch; they cannot bear the sudden light; a general restlessness supervenes; the face of society is disturbed, or perhaps convulsed; old interests, and old beliefs, are destroyed, before new ones have been created. These symptoms are the precursors of revolution; they have preceded all the great changes through which the world has passed; and while, if they are not excessive, they forebode progress, so if they are excessive, they threaten anarchy. It is the business of practical men to moderate such symptoms, and to take care that the truths which philosophers discover, are not applied so rashly as to dislocate the fabric, instead of strengthening it. But the philosopher has only to discover the truth, and promulgate it; and that is hard work enough for any man, let his ability be as great as it may. This division of labour, between thinkers and actors, secures an economy of force, and prevents either class from wasting its power. It establishes a difference between science, which ascertains principles, and art, which applies them. It also recognizes, that the philosopher and the practical man, having each a separate part to play, each is, in his own field, supreme. But it is a sad confusion for either to interfere with the other. In their different spheres, both are independent, and both are worthy of admiration. Inasmuch, however, as practical men should never allow the speculative conclusions of philosophers, whatever be their truth, to be put in actual operation, unless society is, in some degree, ripe for their reception; so, on the other hand, philosophers are not to hesitate, and tremble, and stop short in their career, because their intellect is leading them to conclusions subversive of existing interests. The duty of a philosopher is clear. His path lies straight before him. He must take every pains to ascertain the truth; and, having arrived at a conclusion, he, instead of shrinking from it because it is unpalatable, or because it seems dangerous, should on that very account, cling the closer to it, should uphold it in bad repute, more zealously than he would have done in good repute; should noise it abroad far and wide, utterly regardless what opinions he shocks, or what interests he imperils; should, on its behalf, court hostility and despise contempt, being well assured, that, if it is not true, it will die, but that, if it is true, it must produce ultimate benefit, albeit unsuited for practical adoption by the age or country in which it is first propounded.

But Reid, notwithstanding the clearness of his mind and his great powers of argument, had so little of the real philosophic spirit, that he loved truth, not for its own sake, but for the sake of its immediate and practical results. He himself tells us, that he began to study philosophy, merely because he was shocked at the consequences at which philosophers had arrived. As long as the speculations of Locke and of Berkeley were not pushed to their logical conclusions, Reid acquiesced in them, and they were good in his eyes.[720] While they were safe and tolerably orthodox, he was not over-nice in inquiring into their validity. In the hands of Hume, however, philosophy became bolder and more inquisitive; she disturbed opinions which were ancient, and which it was pleasant to hold; she searched into the foundation of things, and by forcing men to doubt and to inquire, she rendered inestimable service to the cause of truth. But this was precisely the tendency at which Reid was displeased. He saw that such disturbance was uncomfortable; he saw that it was hazardous; therefore, he endeavoured to prove that it was groundless. Confusing the question of practical consequences with the totally different question of scientific truth, he took for granted that, because to his age the adoption of those consequences would be mischievous, they must be false. To the profound views of Hume respecting causation, he gravely objects, that if they were carried into effect, the operation of criminal law would be imperilled.[721] To the speculations of the same philosopher concerning the metaphysical basis of the theory of contracts, he replies, that such speculations perplex men, and weaken their sense of duty; they are, therefore, to be disapproved of, on account of their tendency.[722] With Reid, the main question always is, not whether an inference is true, but what will happen if it is true. He says, that a doctrine is to be judged by its fruits;[723] forgetting that the same doctrine will bear different fruits in different ages, and that the consequences which a theory produces in one state of society, are often diametrically opposed to those which it produces in another. He thus made his own age the standard of all future ones. He also trammelled philosophy with practical considerations; diverting thinkers from the pursuit of truth, which is their proper department, into the pursuit of expediency, which is not their department at all. Reid was constantly stopping to inquire, not whether theories were accurate, but whether it was advisable to adopt them; whether they were favourable to patriotism, or to generosity, or to friendship;[724] in a word, whether they were comfortable, and such as we should at present like to believe.[725] Or else, he would take other ground, still lower, and still more unworthy of a philosopher. In opposing, for instance, the doctrine, that our faculties sometimes deceive us,—a doctrine which, as he well knew, had been held by men whose honesty was equal to his own, and whose ability was superior to his own,—he does not scruple to enlist on his side the prejudices of a vulgar superstition; seeking to blacken the tenet which he was unable to refute. He actually asserts, that they who advocate it, insult the Deity, by imputing to the Almighty that He has lied. Such being the consequence of the opinion, it of course follows that the opinion must be rejected without further scrutiny, since, to accept it, would produce fatal results on our conduct, and would, indeed, be subversive of all religion, of all morals, and of all knowledge.[726]

In 1764, Reid published his Inquiry into the Human Mind; and in that, and in his subsequent work, entitled Essays on the Powers of the Mind, he sought to destroy the philosophy of Locke, Berkeley, and Hume. And as Hume was the boldest of the three, it was chiefly his philosophy which Reid attacked. Of the character of this attack, some specimens have just been given; but they rather concern his object and motives, while what we have now to ascertain is, his method, that is, the tactics of his warfare. He clearly saw, that Hume had assumed certain principles, and had reasoned deductively from them to the facts, instead of reasoning inductively from the facts to them. To this method, he strongly, and perhaps fairly, objects. He admits that Hume had reasoned so accurately, that if his principles were conceded, his conclusions must likewise be conceded.[727] But, he says, Hume had no right to proceed in such a manner. He had no right to assume principles, and then to argue from them. The laws of nature were to be arrived at, not by conjecturing in this way, but by a patient induction of facts.[728] Discoveries depended solely on observation and experiment; and any other plan could only produce theories, ingenious, perhaps, and plausible, but quite worthless.[729] For, theory should yield to fact, and not fact to theory.[730] Speculators, indeed, might talk about first principles, and raise a system by reasoning from them. But, the fact was, that there was no agreement as to how a first principle was to be recognized; since a principle which one man would deem self-evident, another would think it necessary to prove, and a third would altogether deny.[731]

The difficulties of deductive reasoning are here admirably portrayed. It might have been expected, that Reid would have built up his own philosophy according to the inductive plan, and would have despised that assumption of first principles, with which he taunts his opponents. But it is one of the most curious things in the history of metaphysics, that Reid after impeaching the method of Hume, follows the very same method himself. When he is attacking the philosophy of Hume, he holds deduction to be wrong. When he is raising his own philosophy, he holds it to be right. He deemed certain conclusions dangerous, and he objects to their advocates, that they argued from principles, instead of from facts: and that they assumed themselves to be in possession of the first principles of truth, although people were not agreed as to what constituted a first principle. This is well put, and hard to answer. Strange, however, to say, Reid arrives at his own conclusions, by assuming first principles to an extent far greater than had been done by any writer on the opposite side. From them, he argues; his whole scheme is deductive; and his works scarcely contain a single instance of that inductive logic, which, when attacking his opponents, he found it convenient to recommend. It is difficult to conceive a better illustration of the peculiar character of the Scotch intellect in the eighteenth century, and of the firm hold, which, what may be called, the anti-Baconian method, had upon that intellect. Reid was a man of considerable ability, of immaculate honesty, and was deeply convinced that it was for the good of society that the prevailing philosophy should be overthrown. To the performance of that task, he dedicated his long and laborious life; he saw that the vulnerable point of the adverse system was its method; he indicated the deficiencies of that method, and declared, perhaps wrongly, but at all events sincerely, that it could never lead to truth. Yet, and notwithstanding all this, such was the pressure of the age in which he lived, and so completely did the force of circumstances shape his understanding, that, in his own works, he was unable to avoid that very method of investigation which he rebuked in others. Indeed, so far from avoiding it, he was a slave to it. The evidence of this I will now give, because, besides its importance for the history of the Scotch mind, it is valuable as one of many lessons, which teach us how we are moulded by the society which surrounds us; how even our most vigorous actions are influenced by general causes of which we are often ignorant, and which few of us care to study; and, finally, how lame and impotent we are, when, as individuals, we try to stem the onward current, resisting the great progress instead of aiding it, and vainly opposing our little wishes to that majestic course of events, which admits of no interruption, but sweeps on, grand and terrible, while generation after generation passes away, successively absorbed in one mighty vortex.

Directly Reid, ceasing to refute the philosophy of Hume, began to construct his own philosophy, he succumbed to the prevailing method. He now assures us, that all reasoning must be from first principles, and that, so far from reasoning to those principles, we must at once admit them, and make them the basis of all subsequent arguments.[732] Having admitted them, they become a thread to guide the inquirer through the labyrinth of thought.[733] His opponents had no right to assume them, but he might do so, because to him they were intuitive.[734] Whoever denied them, was not fit to be reasoned with.[735] Indeed, to investigate them, or to seek to analyze them, was wrong as well as foolish, because they were part of the constitution of things; and of the constitution of things no account could be given, except that such was the will of God.[736]

As Reid obtained his first principles with such ease, and as he carefully protected them by forbidding any attempt to resolve them into simpler elements, he was under a strong temptation to multiply them almost indefinitely, in order that, by reasoning from them, he might raise a complete and harmonious system of the human mind. To that temptation he yielded with a readiness, which is truly surprising, when we remember how he reproached his opponents with doing the same thing. Among the numerous first principles which he assumes, not only as unexplained, but as inexplicable, are the belief in Personal Identity;[737] the belief in the External World;[738] the belief in the Uniformity of Nature;[739] the belief in the Existence of Life in Others;[740] the belief in Testimony;[741] also in the power of distinguishing truth from error,[742] and even in the correspondence of the face and voice to the thoughts.[743] Of belief generally, he asserts that there are many principles,[744] and he regrets that any one should have rashly attempted to explain them.[745] Such things are mysterious, and not to be pried into. We have also other faculties, which being original and indecomposable, resist all inductive treatment, and can neither be resolved into simpler elements, nor referred to more general laws. To this class, Reid assigns Memory,[746] Perception,[747] Desire of Self-Approbation,[748] and not only Instinct, but even Habit.[749] Many of our ideas, such as those concerning Space and Time, are equally original;[750] and other first principles there are, which have not been enunciated, but from which we may reason.[751] They, therefore, are the major premisses of the argument; no reason having yet been given for them, they must be simple; and not having yet been explained, they are, of course, inexplicable.[752]

All this is arbitrary enough. Still, in justice to Reid, it must be said, that, having made these assumptions, he displayed remarkable ability in arguing from them, and that, in attacking the philosophy of his time, he subjected it to a criticism, which has been extremely serviceable. His lucidity, his dialectic skill, and the racy and masculine style in which he wrote, made him a formidable opponent, and secured to his objections a respectful hearing. To me, however, it appears, that notwithstanding the attempts, first of M. Cousin, and afterwards of Sir William Hamilton, to prop up his declining reputation, his philosophy, as an independent system, is untenable, and will not live. In this I may be mistaken; but what is quite certain is, that nothing can be more absurd than to suppose, as some have done, that he adopted the inductive, or, as it is popularly called, Baconian method. Bacon, indeed, would have smiled at such a disciple, assuming all sorts of major premisses, taking general principles for granted with the greatest recklessness, and reserving his skill for the task of reasoning from propositions for which he had no evidence, except that on a cursory, or, as he termed it, a common-sense, inspection, they appeared to be true.[753] This refusal to analyze preconceived notions, comes under the head of what Bacon stigmatized as the anticipatio naturÆ, and which he deemed the great enemy of knowledge, on account of the dangerous confidence it places in the spontaneous and uncorrected conclusions of the human mind. When, therefore, we find Reid holding up the Baconian philosophy, as a pattern which it behoves all inquirers to follow;[754] and when we, moreover, find Dugald Stewart, who, though a somewhat superficial thinker, was, at all events, a careful writer, supposing that Reid had followed it,[755] we meet with fresh proof of how difficult it was for Scotchmen of the last age to imbibe the true spirit of inductive logic, since they believed, that a system which flagrantly violated its rules, had been framed in strict accordance with them.

Leaving mental philosophy, I now come to physical science, in which, if anywhere, we might expect that the inductive plan would predominate, and would triumph over the opposite, or deductive, one. How far this was the case, I will endeavour to ascertain, by an examination of the most important discoveries which have been made by Scotchmen concerning the organic and inorganic world. And, as my object is merely to indicate the turn and character of the Scotch mind, I shall avoid all details respecting the practical effects of those discoveries, and shall confine myself to such a narration as will exhibit their purely scientific aspect, so as to enable the reader to understand what additions were made to our knowledge of the laws of nature, and in what way the additions were made. The character of each discovery, and its process, will be stated, but nothing more. Neither here, nor in any part of this Introduction, do I pretend to investigate questions of practical utility, or to trace the connexion between the discoveries of science and the arts of life. That I shall do in the body of the work itself, where I hope to explain a number of minute social events, many of which are regarded as isolated, if not incongruous. For the present, I solely aim at those broad principles, which, by marking out the epochs of thought, underlie the whole fabric of society, and which must be clearly apprehended before history can cease to be a mere empirical assemblage of facts, of which the scientific basis being unsettled, the true order and coherence must be unknown.

Among the sciences which concern the inorganic world, the laws of heat occupy a conspicuous place. On the one hand, they are connected with geology, being intimately allied, and, indeed, necessarily bound up, with every speculation respecting the changes and present condition of the crust of the earth. On the other hand, they touch the great questions of life, both animal and vegetable; they have to do with the theory of species, and of race; they modify soil, food, and organization; and to them we must look for valuable help towards solving those great problems in biology, which, of late years, have occupied the attention of the boldest and most advanced philosophers.

Our present knowledge of the laws of heat, may be briefly stated as branching into five fundamental divisions. These are: latent heat; specific heat; the conduction of heat; the radiation of heat; and, finally, the undulatory theory of heat; by which last, we are gradually discarding our old material views, and are accustoming ourselves to look upon heat as simply one of the forms of force, all of which, such as light, electricity, magnetism, motion, gravitation, and chemical affinity, are constantly assuming each other's shape, but, in their total amount, are incapable either of increase or of diminution.[756] This grand conception, which is now placing the indestructibility of force on the same ground as the indestructibility of matter, has an importance far above its scientific value, considerable as that undoubtedly is. For, by teaching us, that nothing perishes, but that, on the contrary, the slightest movement of the smallest body, in the remotest region, produces results which are perpetual, which diffuse themselves through all space, and which, though they may be metamorphosed, cannot be destroyed, it impresses us with such an exalted idea of the regular and compulsory march of physical affairs, as must eventually influence other and higher departments of inquiry. Our habits of thought are so connected and interwoven, that notions of law and of the necessary concatenation of things, can never be introduced into one field of speculation, without affecting other fields which lie contiguous to it. When, therefore, the modern doctrine of conservation of force,[757] becomes firmly coupled with the older doctrine of conservation of matter, we may rest assured that the human mind will not stop there, but will extend to the study of Man, inferences analogous to those already admitted in the study of Nature. Having once recognized that the condition of the material universe, at any one moment, is simply the result of every thing which has happened at all preceding moments, and that the most trivial disturbance would so violate the general scheme, as to render anarchy inevitable, and that, to sever from the total mass even the minutest fragment, would, by dislocating the structure, bury the whole in one common ruin, we, thus admitting the exquisite adjustment of the different parts, and discerning, too, in the very beauty and completeness of the design, the best proof that it has never been tampered with by the Divine Architect, who called it into being, in whose Omniscience both the plan, and the issue of the plan, resided with such clearness and unerring certainty, that not a stone in that superb and symmetrical edifice has been touched since the foundation of the edifice was laid, are, by ascending to this pitch and elevation of thought, most assuredly advancing towards that far higher step, which it will remain for our posterity to take, and which will raise their view to so commanding a height, as to insure the utter rejection of those old and eminently irreligious dogmas of supernatural interference with the affairs of life, which superstition has invented, and ignorance has bequeathed, and the present acceptance of which betokens the yet early condition of our knowledge, the penury of our intellectual resources, and the inveteracy of the prejudices in which we are still immersed.

It is, therefore, natural, that the physical doctrine of indestructibility applied to force as well as to matter, should be essentially a creation of the present century, notwithstanding a few allusions made to it by some earlier thinkers, all of whom, however, groped vaguely, and without general purpose. No preceding age was bold enough to embrace so magnificent a view as a whole, nor had any preceding philosophers sufficient acquaintance with nature to enable them to defend such a conception, even had they desired to entertain it. Thus, in the case now before us, it is evident, that while heat was believed to be material, it could not be conceived as a force, and therefore no one could grasp the theory of its metamorphosis into other forces; though there are passages in Bacon which prove that he wished to identify it with motion. It was first necessary to abstract heat into a mere property or affection of matter, and there was no chance of doing this until heat was better understood in its immediate antecedents, that is, until, by the aid of mathematics, its proximate laws had been generalized. But, with the single exception of Newton, whose efforts, notwithstanding his gigantic powers, were, on this subject, very unsatisfactory, and who, moreover, had a decided leaning towards the material theory, no one attempted to unravel the mathematical laws of heat till the latter half of the eighteenth century, when Lambert and Black began the career which Prevost and Fourier followed up. The mind, having been so slow in mastering the preliminaries and outworks of the inquiry, was not ripe for the far more difficult enterprise of idealizing heat itself, and so abstracting it, as to strip it of its material attributes, and leave it to nothing but the speculative notion of an immaterial force.

From these considerations, which were necessary to enable the reader to appreciate the value of what was done in Scotland, it will be seen how essential it was that the laws of the movement of heat should be studied before its nature was investigated, and before the emission theory could be so seriously attacked as to allow of the possibility of that great doctrine of the indestructibility of force, which, I make no doubt, is destined to revolutionize our habits of thought, and to give to future speculations a basis infinitely wider than any previously known. In regard to the movements of heat, we owe the laws of conduction and of radiation chiefly to France and Geneva, while the laws of specific heat, and those of latent heat, were discovered in Scotland. The doctrine of specific heat, though interesting, has not the scientific importance which belongs to the other departments of this great subject; but the doctrine of latent heat is extremely curious, not only in itself, but also on account of the analogies it suggests with various branches of physical inquiry.

What is termed latent heat, is exhibited in the following manner. If, in consequence of the application of heat, a solid passes into a liquid, as ice, for instance, into water, the conversion occupies a longer time than could be explained by any theory which had been propounded down to the middle of the eighteenth century. Neither was it possible to explain how it is, that ice never rises above the temperature of 32° until it is actually melted, no matter what the heat of the adjacent bodies may be. There were no means of accounting for these circumstances. And though practical men, being familiar with them, did not wonder at them, they caused great astonishment among thinkers, who were accustomed to analyze events, and to seek a reason for common and every-day occurrences.

Soon after the middle of the eighteenth century, Black, who was then one of the professors in the University of Glasgow, turned his attention to this subject.[758] He struck out a theory which, being eminently original, was violently attacked, but is now generally admitted. With a boldness and reach of thought not often equalled, he arrived at the conclusion, that whenever a body loses some of its consistence, as in the case of ice becoming water, or water becoming steam, such body receives an amount of heat which our senses, though aided by the most delicate thermometer, can never detect. For, this heat is absorbed; we lose all sight of it, and it produces no palpable effect on the material world, but becomes, as it were, a hidden property. Black, therefore, called it latent heat, because, though we conceive it as an idea, we cannot trace it as a fact. The body is, properly speaking, hotter; and yet its temperature does not rise. Directly, however, the foregoing process is inverted, that is to say, directly the steam is condensed into water, or the water hardened into ice, the heat returns into the world of sense; it ceases to be latent, and communicates itself to the surrounding objects. No new heat has been created; it has, indeed, appeared and disappeared, so far as our senses are concerned; but our senses were deceived, since there has, in truth, been neither addition nor diminution.[759] That this remarkable theory paved the way for the doctrine of the indestructibility of force, will be obvious to whoever has examined the manner in which, in the history of the human mind, scientific conceptions are generated. The process is always so slow, that no single discovery has ever been made, except by the united labours of several successive generations. In estimating, therefore, what each man has done, we must judge him, not by the errors he commits, but by the truths he propounds. Most of his errors are not really his own. He inherits them from his predecessors; and if he throws some of them off, we should be grateful, instead of being dissatisfied that he has not rejected all. Black, no doubt, fell into the error of regarding heat as a material substance, which obeys the laws of chemical composition.[760] But this was merely an hypothesis, which was bequeathed to him, and with which the existing state of thought forced him to encumber his theory. He inherited the hypothesis, and could not get rid of his troublesome possession. The real service which he rendered is, that, in spite of that hypothesis, which clung to him to the last, he, far more than any of his contemporaries, contributed towards the great conception of idealizing heat, and thus enabled his successors to admit it into the class of immaterial and supersensual forces. Once admitted into that class, the list of forces became complete; and it was comparatively easy to apply to the whole body of force, the same notion of indestructibility, which had previously been applied to the whole body of matter. But it was hardly possible to effect this object, while heat stood, as it were, midway between force and matter, yielding opposite results to different senses; amenable to the touch, but invisible to the eye. What was wanting, was to remove it altogether out of the jurisdiction of the senses, and to admit that, though we experience its effects, we can only conceive its existence. Towards accomplishing this, Black took a prodigious stride. Unconscious, perhaps, of the remote tendency of his own labours, he undermined that doctrine of material heat, which he seemed to support. For, by his advocacy of latent heat, he taught that its movements constantly baffle, not only some of our senses, but all of them; and that, while our feelings make us believe that heat is lost, our intellect makes us believe that it is not lost. Here, we have apparent destructibility, and real indestructibility. To assert that a body received heat without its temperature rising, was to make the understanding correct the touch, and defy its dictates. It was a bold and beautiful paradox, which required courage as well as insight to broach, and the reception of which marks an epoch in the human mind, because it was an immense step towards idealizing matter into force. Some, indeed, have spoken of invisible matter; but that is a contradiction in terms, which will never be admitted, as long as the forms of speech remain unchanged. Nothing can be invisible, except force, mind, and the Supreme Cause of all. We must, therefore, ascribe to Black the signal merit that he first, in the study of heat, impeached the authority of the senses, and thereby laid the foundation of every thing which was afterwards done. Besides the relation which his discovery bears to the indestructibility of force, it is also connected with one of the most splendid achievements effected by this generation in inorganic physics; namely, the establishment of the identity of light and heat. To the senses, light and heat, though in some respects similar, are in most respects dissimilar. Light, for instance, affects the eye, and not the touch. Heat affects the touch, but, under ordinary circumstances, does not affect the eye. The capital difference, however, between them is, that heat, unlike light, possesses the property of temperature; and this property is so characteristic, that until our understandings are invigorated by science, we cannot conceive heat separated from temperature, but are compelled to confuse one with the other. Directly, however, men began to adopt the method followed by Black, and were resolved to consider heat as supersensual, they entered the road which led to the discovery of light and heat being merely different developments of the same force. Ignoring the effects of heat on themselves, or on any part of the creation, which was capable of feeling its temperature, and would therefore be deceived by it, nothing was left for them to do, but to study its effects on the inanimate world. Then, all was revealed. The career of discovery was fairly opened; and analogies between light and heat, which even the boldest imagination had hardly suspected, were placed beyond a doubt. To the reflection of heat, which had been formerly known, were now added the refraction of heat, its double refraction, its polarization, its depolarization, its circular polarization, the interference of its rays, and their retardation; while, what is more remarkable than all, the march of our knowledge on these points was so swift, that before the year 1836 had come to a close, the chain of evidence was completed by the empirical investigations of Forbes and Melloni, they themselves little witting that every thing which they accomplished was prepared before they were born, that they were but the servants and followers of him who indicated the path in which they trod, and that their experiments, ingenious as they were, and full of resource, were simply the direct practical consequence of one of those magnificent ideas which Scotland has thrown upon the world, and the memory of which is almost enough so to bribe the judgment, as to tempt us to forget, that, while the leading intellects of the nation were engaged in such lofty pursuits, the nation itself, untouched by them, passed them over with cold and contemptuous indifference, being steeped in that deadening superstition, which turns a deaf ear to every sort of reason, and will not hearken to the voice of the charmer, charm he never so wisely.

By thus considering the descent and relationship of scientific conceptions, we can alone understand what we really owe to Black's discovery of latent heat. In regard to the method of the discovery, little need be said, since every student of the Baconian philosophy must see, that the discovery was of a kind for which none of the maxims of that system had provided. As latent heat escapes the senses, it could not obey the rules of a philosophy, which grounds all truth on observation and experiment. The subject of the inquiry being supersensual, there was no scope for what Bacon called crucial experiments and separations of nature. The truth was in the idea; experiments, therefore, might illustrate it, might bring it up to the surface, and so enable men to grasp it, but could not prove it. And this, which appears on the very face of the discovery, is confirmed by the express testimony of Dr. Thomson, who knew Black, and was, indeed, one of the most eminent of his pupils. We are assured by this unimpeachable witness, that Black, about the year 1759 began to speculate concerning heat; that the result of those speculations was the theory of latent heat; that he publicly taught that theory in the year 1761; but that the experiments which were necessary to convince the world of it were not made till 1764,[761] though, as I need hardly add, according to the inductive method, it was a breach of all the rules of philosophy to be satisfied with the theory three years before the experiments were made, and it was a still greater breach, not only to be satisfied with it, but to have openly promulgated it as an original and unquestionable truth, which explained, in a new manner, the economy of the material world.

The intellect of Black belonged to a class, which, in the eighteenth century, was almost universal in Scotland, but was hardly to be found in England, and which, for want of a better word, we are compelled to call deductive, though fully admitting that even the most deductive minds have in them a large amount of induction, since, indeed, without induction, the common business of life could not be carried on. But for the purposes of scientific classification, we may say, that a man or an age is deductive, when the favourite process is reasoning from principles instead of reasoning to them, and when there is a tendency to underrate the value of specific experience. That this was the case with the illustrious discoverer of latent heat, we have seen, both from the nature of the discovery, and from the decisive testimony of his friend and pupil. And a further confirmation may be found in the circumstance, that, having once propounded his great idea, he, instead of instituting a long series of laborious experiments, by which it might be verified in its different branches, preferred reasoning from it according to the general maxims of dialectic; pushing it to its logical consequences, rather than tracking it into regions where the senses might either confirm or refute it.[762] By following this process of thought, he was led to some beautiful speculations, which are so remote from experience, that even now, with all the additional resources of our knowledge, we cannot tell whether they are true or false. Of this kind were his views respecting the causes of the preservation of man, whose existence would, he thought, be endangered, except for the power which heat possesses of lying latent and unobserved. Thus, for example, when a long and severe winter was followed by sudden warmth, it appeared natural that the ice and snow should melt with corresponding suddenness; and if this were to happen, the result would be such terrible inundations, that it would be hardly possible for man to escape from their ravages. Even if he escaped, his works, that is, the material products of his civilization, would perish. From this catastrophe, nothing saves him but the latent power of heat. Owing to this power, directly the ice and snow begin to melt at their surface, the heat enters their structure, where a large part of it remains in abeyance, and thus losing much of its power, the process of liquefaction is arrested. This dreadful agent is lulled, and becomes dormant. It is weakened at the outset of its career, and is laid up, as in a storehouse, from which it can afterwards emerge, gradually, and with safety to the human species.[763]

In this way, as summer advances, a vast magazine of heat is accumulated, and is preserved in the midst of water, where it can do man no injury, since, indeed, his senses are unable to feel it. There the heat remains buried, until, in the rotation of the seasons, winter returns, and the waters are congealed into ice. In the process of congelation, that treasury of heat, which had been hidden all the summer, reappears; it ceases to be latent; and now, for the first time, striking the senses of man, it tempers, on his behalf, the severity of winter. The faster the water freezes, the faster the heat is disengaged; so that, by virtue of this great law of nature, cold actually generates warmth, and the inclemency of every season, though it cannot be hindered, is softened in proportion as the inclemency is more threatening.[764]

Thus, again, inasmuch as heat becomes latent, and flies from the senses, not only when ice is passing into water, but also when water is passing into steam, we find in this latter circumstance, one of the reasons why man and other animals can live in the tropics, which, but for this, would be deserted. They are constantly suffering from the heat which is collected in their bodies, and which, considered by itself, is enough to destroy them. But this heat causes thirst, and they consequently swallow great quantities of fluid, much of which exudes through the pores of the skin in the form of vapour. And as, according to the theory of latent heat, vapour cannot be produced without a vast amount of heat being buried within it, such vapour absorbs and carries off from the body, that which, if left in the system, would prove fatal. To this we must add, that, in the tropics, the evaporation of water is necessarily rapid, and the vapour which is thus produced, becomes another storehouse of heat, and a vehicle by which it is removed from the earth, and prevented from unduly interfering with the economy of life.[765]

From these and many other arguments, all of which were so essentially speculative, and dealt with such hidden processes of nature, that even now we are not justified either in confidently admitting them or in positively denying them, Black was led to that great doctrine of the indestructibility of heat,[766] which, as I have pointed out, has, in its connexion with the indestructibility of force, a moral and social importance even superior to its scientific value. Though the evidence of which he was possessed was far more scanty than what we now have, he, by the reach of his commanding intellect, rather than by the number and accuracy of his facts, became so penetrated with a conviction of the stability of physical affairs, that he not only applied that idea to the subtle phenomena of heat, but, what was much harder to do, he applied it to cases in which heat so entirely escapes the senses, that man has no cognizance of it, except through the medium of the imagination. According to his view, heat passes through an immense variety of changes, during which it appears to be lost; changes which no eye can ever see, which no touch can ever experience, and which no instrument can ever measure. Still, and in the midst of all these changes, it remains intact. From it nothing can be taken, and to it nothing can be added. In one of those fine passages of his Lectures, which, badly reported as they are,[767] bear the impress of his elevated genius, Black, after stating what would probably happen, if the total amount of heat existing in the world were to be diminished, proceeds to speculate on the consequences of its being increased. Were it possible for any power to add to it ever so little, it would at once overstep its bounds; the equilibrium would be disturbed; the framework of affairs would be disjointed. The evil rapidly increasing, and acting with accumulated force, nothing would be able to stop its ravages. It must continue to gain ground, till all other principles are absorbed and conquered. Sweeping on, unhindered, and irresistible, before it, every animal must perish, the whole vegetable world must disappear, the waters must pass into vapour, and the solid parts of the globe be merged and melted, until, at length, the glorious fabric, loosened and dissolved, would fall away, and return to that original chaos out of which it had been evolved.[768]

These, like many other of the speculations of this great thinker, will find small favour with those purely inductive philosophers, who not only suppose, perhaps rightly, that all our knowledge is in its beginning built upon facts, but who countenance, what seems to me, the very dangerous opinion, that every increase of knowledge must be preceded by an increase of facts. To such men it will appear, that Black had far better have occupied himself in making new observations, or devising new experiments, than in thus indulging his imagination in wild and unprofitable dreams. They will think, that these flights of fancy are suitable, indeed, to the poet, but unworthy of that severe accuracy, and of that close attention to facts, which ought to characterize a philosopher. In England, especially, there is, among physical inquirers, an avowed determination to separate philosophy from poetry, and to look upon them, not only as different, but as hostile. Among that class of thinkers, whose zeal and ability are beyond all praise, and to whom we owe almost unbounded obligations, there does undoubtedly exist a very strong opinion, that, in their own pursuit, the imagination is extremely dangerous, as leading to speculations, of which the basis is not yet assured, and generating a desire to catch too eagerly at distant glimpses before the intermediate ground has been traversed. That the imagination has this tendency is undeniable. But they who object to it on this account, and who would, therefore, divorce poetry from philosophy, have, I apprehend, taken a too limited view of the functions of the human mind, and of the manner in which truth is obtained. There is, in poetry, a divine and prophetic power, and an insight into the turn and aspect of things, which, if properly used, would make it the ally of science instead of the enemy. By the poet, nature is contemplated on the side of the emotions; by the man of science, on the side of the understanding. But the emotions are as much a part of us as the understanding: they are as truthful; they are as likely to be right. Though their view is different, it is not capricious. They obey fixed laws; they follow an orderly and uniform course; they run in sequences; they have their logic and method of inference. Poetry, therefore, is a part of philosophy, simply because the emotions are a part of the mind. If the man of science despises their teaching, so much the worse for him. He has only half his weapons; his arsenal is unfilled. Conquests, indeed, he may make, because his native strength may compensate the defects of his equipment. But his success would be more complete and more rapid, if he were properly furnished and made ready for the battle. And I cannot but regard as the worst intellectual symptom of this great country, what I must venture to call the imperfect education of physical philosophers, as exhibited both in their writings and in their trains of thought. This is the more serious, because they, as a body, form the most important class in England, whether we look at their ability, or at the benefits we have received from them, or at the influence they are exercising, and are likely to exercise, over the progress of society. It cannot, however, be concealed, that they display an inordinate respect for experiments, an undue love of minute detail, and a disposition to overrate the inventors of new instruments, and the discoverers of new, but often insignificant, facts. Their predecessors of the seventeenth century, by using hypotheses more boldly, and by indulging their imagination more frequently, did certainly effect greater things, in comparison with the then state of knowledge, than our contemporaries, with much superior resources, have been able to achieve. The magnificent generalizations of Newton and Harvey could never have been completed in an age absorbed in one unvarying round of experiments and observations. We are in that predicament, that our facts have outstripped our knowledge, and are now encumbering its march. The publications of our scientific institutions, and of our scientific authors, overflow with minute and countless details, which perplex the judgment, and which no memory can retain. In vain do we demand that they should be generalized, and reduced into order. Instead of that, the heap continues to swell. We want ideas, and we get more facts. We hear constantly of what nature is doing, but we rarely hear of what man is thinking. Owing to the indefatigable industry of this and the preceding century, we are in possession of a huge and incoherent mass of observations, which have been stored up with great care, but which, until they are connected by some presiding idea, will be utterly useless. The most effective way of turning them to account, would be to give more scope to the imagination, and incorporate the spirit of poetry with the spirit of science. By this means, our philosophers would double their resources, instead of working, as now, maimed, and with only half their nature. They fear the imagination, on account of its tendency to form hasty theories. But, surely, all our faculties are needed in the pursuit of truth, and we cannot be justified in discrediting any part of the human mind. And I can hardly doubt, that one of the reasons why we, in England, made such wonderful discoveries during the seventeenth century, was because that century was also the great age of English poetry. The two mightiest intellects our country has produced are Shakspeare and Newton; and that Shakspeare should have preceded Newton, was, I believe, no casual or unmeaning event. Shakspeare and the poets sowed the seed, which Newton and the philosophers reaped. Discarding the old scholastic and theological pursuits, they drew attention to nature, and thus became the real founders of all natural science. They did even more than this. They first impregnated the mind of England with bold and lofty conceptions. They taught the men of their generation to crave after the unseen. They taught them to pine for the ideal, and to rise above the visible world of sense. In this way, by cultivating the emotions, they opened one of the paths which lead to truth. The impetus which they communicated, survived their own day, and, like all great movements, was felt in every department of thought. But now it is gone; and, unless I am greatly mistaken, physical science is at present suffering from its absence. Since the seventeenth century, we have had no poet of the highest order, though Shelley, had he lived, would perhaps have become one. He had something of that burning passion, that sacred fire, which kindles the soul, as though it came fresh from the altar of the gods. But he was cut off in his early prime, when his splendid genius was still in its dawn. If we except his immature, though marvellous, efforts, we may assuredly say, that, for nearly two hundred years, England has produced no poetry which bears those unmistakable marks of inspiration which we find in Spenser, in Shakspeare, and in Milton. The result is, that we, separated by so long an interval from those great feeders of the imagination, who nurtured our ancestors, and being unable to enter fully into the feelings of poets, who wrote when nearly all opinions, and, therefore, nearly all forms of emotion, were very different to what they now are, cannot possibly sympathize with those immortal productions so closely as their contemporaries did. The noble English poetry of the sixteenth and seventeenth centuries is read more than ever, but it does not colour our thoughts; it does not shape our understandings, as it shaped the understandings of our forefathers. Between us and them is a chasm, which we cannot entirely bridge. We are so far removed from the associations amid which those poems were composed, that they do not flash upon us with that reality and distinctness of aim, which they would have done, had we lived when they were written. Their garb is strange, and belongs to another time. Not merely their dialect and their dress, but their very complexion and their inmost sentiments, tell of bygone days, of which we have no firm hold. There is, no doubt, a certain ornamental culture, which the most highly educated persons receive from the literature of the past, and by which they sometimes refine their taste, and sometimes enlarge their ideas. But the real culture of a great people, that which supplies each generation with its principal strength, consists of what is learnt from the generation immediately preceding. Though we are often unconscious of the process, we build nearly all our conceptions on the basis recognized by those who went just before us. Our closest contact is, not with our forefathers, but with our fathers. To them we are linked by a genuine affinity, which, being spontaneous, costs us no effort, and from which, indeed, we cannot escape. We inherit their notions, and modify them, just as they modified the notions of their predecessors. At each successive modification, something is lost and something is gained, until, at length, the original type almost disappears. Therefore it is, that ideas entertained several generations ago, bear about the same relation to us, as ideas preserved in a foreign literature. In both cases, the ideas may adorn our knowledge, but they are never so thoroughly incorporated with our minds, as to be the knowledge itself. The assimilation is incomplete, because the sympathy is incomplete. We have now no great poets; and our poverty in this respect is not compensated by the fact, that we once had them, and that we may, and do, read their works. The movement has gone by; the charm is broken; the bond of union, though not cancelled, is seriously weakened. Hence, our age, great as it is, and, in nearly all respects, greater than any the world has yet seen, has, notwithstanding its large and generous sentiments, its unexampled toleration, its love of liberty, and its profuse, and almost reckless, charity, a certain material, unimaginative, and unheroic character, which has made several observers tremble for the future. So far as I can understand our present condition, I do not participate in these fears, because I believe that the good we have already gained, is beyond all comparison greater than what we have lost. But that something has been lost, is unquestionable. We have lost much of that imagination, which, though, in practical life, it often misleads, is, in speculative life, one of the highest of all qualities, being suggestive as well as creative. Even practically, we should cherish it, because the commerce of the affections mainly depends on it. It is, however, declining; while, at the same time, the increasing refinement of society accustoms us more and more to suppress our emotions, lest they should be disagreeable to others. And as the play of the emotions is the chief study of the poet, we see, in this circumstance, another reason which makes it difficult to rival that great body of poetry which our ancestors possessed. Therefore, it is doubly incumbent on physical philosophers to cultivate the imagination. It is a duty they owe to their own pursuits, which would be enriched and invigorated by such an enlargement of their resources. It is also a duty which they owe to society in general; since they, whose intellectual influence is already greater than that of any other class, and whose authority is perceptibly on the increase, might have power enough to correct the most serious deficiency of the present age, and to make us some amends for our inability to produce such a splendid imaginative literature as that which our forefathers created, and in which the choicest spirits of the seventeenth century did, if I may so say, dwell and have their being.

If, therefore, Black had done nothing more than set the example of a great physical philosopher giving free scope to the imagination, he would have conferred upon us a boon, the magnitude of which it is not easy to overrate. And it is very remarkable, that, before he died, that department of inorganic physics, which he cultivated with such success, was taken up by another eminent Scotchman, who pursued exactly the same plan, though with somewhat inferior genius. I allude, of course, to Leslie, whose researches on heat are well known to those who are occupied with this subject; while, for our present purpose, they are chiefly interesting as illustrating that peculiar method which, in the eighteenth century, seemed essential to the Scotch mind.

About thirty years after Black propounded his famous theory of heat, Leslie began to investigate the same topic, and, in 1804, published a special dissertation upon it.[769] In that work, and in some papers in his Treatises on Philosophy, are contained his views, several of which are now known to be inaccurate,[770] though some are of sufficient value to mark an epoch in the history of science. Such was his generalization respecting the connexion between the radiation of heat, and its reflection; bodies which reflect it most, radiating it least, and those which radiate it most, reflecting it least. Such, too, was another wide conclusion, which the best inquirers have since confirmed, namely, that, while heat is radiating from a body, the intensity of each ray is as the sine of the angle which it makes with the surface of that body.

These were important steps, and they were the result of experiments, preceded by large and judicious hypotheses. In relation, however, to the economy of nature, considered as a whole, they are of small account in comparison with what Leslie effected towards consolidating the great idea of light and heat being identical, and thus preparing his contemporaries for that theory of the interchange of forces, which is the capital intellectual achievement of the nineteenth century. But it is interesting to observe, that, with all his ardour, he could not go beyond a certain length. He was so hampered by the material tendencies of his time, that he could not bring himself to conceive heat as a purely supersensual force, of which temperature was the external manifestation.[771] For this, the age was barely ripe. We accordingly find him asserting, that heat is an elastic fluid, extremely subtle, but still a fluid.[772] His real merit was, that, notwithstanding the difficulties which beset his path, he firmly seized the great truth, that there is no fundamental difference between light and heat. As he puts it, each is merely a metamorphosis of the other. Heat is light in complete repose. Light is heat in rapid motion. Directly light is combined with a body, it becomes heat; but when it is thrown off from that body, it again becomes light.[773]

Whether this is true or false, we cannot tell; and many years, perhaps many generations, will have to elapse before we shall be able to tell. But the service rendered by Leslie is quite independent of the accuracy of his opinion, as to the manner in which light and heat are interchanged. That they are interchanged, is the essential and paramount idea. And we must remember, that he made this idea the basis of his researches, at a period when some very important facts, or, I should rather say, some very conspicuous facts, were opposed to it; while the main facts which favoured it were still unknown. When he composed his work, the analogies between light and heat, with which we are now acquainted, had not been discovered; no one being aware, that double refraction, polarization, and other curious properties, are common to both. To grasp so wide a truth in the face of such obstacles, was a rare stroke of sagacity. But, on account of the obstacles, the inductive mind of England refused to receive the truth, as it was not generalized from a survey of all the facts. And Leslie, unfortunately for himself, died too soon to enjoy the exquisite pleasure of witnessing the empirical corroboration of his doctrine by direct experiment, although he clearly perceived that the march of discovery, in reference to polarization, was leading the scientific world to a point, of which his keen eye had discerned the nature, when, to others, it was an almost invisible speck, dim in the distant offing.[774]

In regard to the method adopted by Leslie, he assures us, that, in assuming the principles from which he reasoned, he derived great aid from poetry; for he knew that the poets are, after their own manner, consummate observers, and that their united observations form a treasury of truths, which are nowise inferior to the truths of science, and of which science must either avail herself, or else suffer from neglecting them.[775] To apply these truths rightly, and to fit them to the exigencies of physical inquiry, is, no doubt, a most difficult task, since it involves nothing less than holding the balance between the conflicting claims of the emotions and the understanding. Like all great enterprises, it is full of danger, and, if undertaken by an ordinary mind, would certainly fail. But there are two circumstances which make it less dangerous in our time, than in any earlier period. The first circumstance is, that the supremacy of the human understanding, and its right to judge all theories for itself, is now more generally admitted than ever; so that there can be little fear of our leaning to the opposite side, and allowing poetry to encroach on science. The other circumstance is, that our knowledge of the laws of nature is much greater than that possessed by any previous age; and there is, consequently, less risk of the imagination leading us into error, inasmuch as we have a large number of well-ascertained truths, which we can confront with every speculation, no matter how plausible or ingenious it may appear.

On both these grounds, Leslie was, I apprehend, justified in taking the course which he did. At all events, it is certain, that, by following it, he came nearer than would otherwise have been possible, to the conceptions of the most advanced scientific thinkers of our day. He distinctly recognized that, in the material world, there is neither break nor pause; so that what we call the divisions of nature have no existence, except in our minds.[776] He was even almost prepared to do away with that imaginary difference between the organic and inorganic world, which still troubles many of our physicists, and prevents them from comprehending the unity and uninterrupted march of affairs. They, with their old notions of inanimate matter, are unable to see that all matter is living, and that what we term death is a mere expression by which we signify a fresh form of life. Towards this conclusion, all our knowledge is now converging; and it is certainly no small merit in Leslie, that he, sixty years ago, when really comprehensive views, embracing the whole creation, were scarcely known among scientific men, should have strongly insisted that all forces are of the same kind, and that we have no right to distinguish between them, as if some were living, and others were dead.[777]

We owe much to him, by whom such views were advocated. But they were then, and in a certain, though far smaller degree, they are now, so out of the domain of physical experience, that Leslie never could have obtained them by generalizing in the way which the inductive philosophy enjoins. His great work on heat was executed, as well as conceived, on the opposite plan;[778] and his prejudices on this point were so strong, that we are assured by his biographer, that he would allow no merit to Bacon, who organized the inductive method into a system, and to whose authority we in England pay a willing, and I had almost said a servile, homage.[779]

Another curious illustration of the skill with which the Scotch mind, when once possessed of a principle, worked from it deductively, appears in the geological speculations of Hutton, late in the eighteenth century. It is well known, that the two great powers which have altered the condition of our planet, and made it what it is, are fire and water. Each has played so considerable a part, that we can hardly measure their relative importance. Judging, however, from the present appearance of the crust of the earth, there is reason to believe, that the older rocks are chiefly the result of fusion, and that the younger are aqueous deposits. It is, therefore, not unlikely, that, in the order in which the energies of nature have unfolded themselves, fire preceded water, and was its necessary precursor.[780] But, all that we are as yet justified in asserting is, that these two causes, the igneous and the aqueous, were in full operation long before man existed, and are still busily working. Perhaps they are preparing another change in our habitation, suitable to new forms of life, as superior to man, as man is superior to the beings who occupied the earth before his time. Be this as it may, fire and water are the two most important and most general principles with which geologists are concerned; and though, on a superficial view, each is extremely destructive, it is certain that they can really destroy nothing, but can only decompose and recompose; shifting the arrangements of nature, but leaving nature herself intact. Whether one of these elements will ever again get the upper hand of its opponent, is a speculation of extreme interest. For, there is reason to suspect, that, at one period, fire was more active than water, and that, at another period, water was more active than fire. That they are engaged in incessant warfare, is a fact with which geologists are perfectly familiar, though, in this, as in many other cases, the poets were the first to discern the truth. To the eye of the geologist, water is constantly labouring to reduce all the inequalities of the earth to a single level; while fire, with its volcanic action, is equally busy in restoring those inequalities, by throwing up matter to the surface, and in various ways disturbing the crust of the globe.[781] And as the beauty of the material world mainly depends on that irregularity of aspect, without which scenery would have presented no variety of form, and but little variety of colour, we shall, I think, not be guilty of too refined a subtlety, if we say that fire, by saving us from the monotony to which water would have condemned us, has been the remote cause of that development of the imagination which has given us our poetry, our painting, and our sculpture, and has thereby not only wonderfully increased the pleasures of life, but has imparted to the human mind a completeness of function, to which, in the absence of such a stimulus, it could not have attained.

When geologists began to study the laws according to which fire and water had altered the structure of the earth, two different courses were open to them, namely, the inductive and the deductive. The deductive plan was to compute the probable consequences of fire and water, by reasoning from the sciences of thermotics and hydrodynamics; tracking each element by an independent line of argument, and afterwards coÖrdinating into a single scheme the results which had been separately obtained. It would then only remain to inquire, how far this imaginary scheme harmonized with the actual state of things; and if the discrepancy between the ideal and the actual were not greater than might fairly be expected from the perturbations produced by other causes, the ratiocination would be complete, and geology would, in its inorganic department, become a deductive science. That our knowledge is ripe for such a process, I am far, indeed, from supposing; but this is the path which a deductive mind would take, so far as it was able. On the other hand, an inductive mind, instead of beginning with fire and water, would begin with the effects which fire and water had produced, and would first study these two agents, not in their own separate sciences, but in their united action as exhibited on the crust of the earth. An inquirer of this sort would assume, that the best way of arriving at truth would be to proceed from effects to causes, observing what had actually happened, and rising from the complex results up to a knowledge of the simple agents, by whose power the results have been brought about.

If the reader has followed the train of thought which I have endeavoured to establish in this chapter, and in the first volume, he will be prepared to expect that when, in the latter half of the eighteenth century, geology was first seriously studied, the inductive plan of proceeding from effects to causes became the favourite one in England; while the deductive plan of proceeding from causes to effects, was adopted in Scotland and in Germany. And such was really the case. It is generally admitted, that, in England, scientific geology owes its origin to William Smith, whose mind was singularly averse to system, and who, believing that the best way of understanding former causes was to study present effects, occupied himself, between the years 1790 and 1815, in a laborious examination of different strata.[782] In 1815, he, after traversing the whole of England on foot, published the first complete geological map which ever appeared, and thus took the first great step towards accumulating the materials for an inductive generalization.[783] In 1807, and, therefore, before he had brought his arduous task to an end, there was formed in London the Geological Society, the express object of which, we are assured, was, to observe the condition of the earth, but by no means to generalize the causes which had produced that condition.[784] The resolution was, perhaps, a wise one. At all events, it was highly characteristic of the sober and patient spirit of the English intellect. With what energy and unsparing toil it has been executed, and how the most eminent members of the Geological Society have, in the pursuit of truth, not only explored every part of Europe, but examined the shell of the earth in America and in Northern Asia, is well known to all who are interested in these matters; nor can it be denied, that the great works of Lyell and Murchison prove that the men who are capable of such laborious enterprises, are also capable of the still more difficult achievement of generalizing their facts and refining them into ideas. They did not go as mere observers, but they went with the noble object of making their observations subservient to a discovery of the laws of nature. That was their aim; and all honour be to them for it. Still, it is evident, that their process is essentially inductive; it is a procedure from the observation of complex phenomena, up to the elements to which those phenomena are owing; it is, in other words, a study of natural effects, in order to learn the operation of natural causes.

Very different was the process in Germany and Scotland. In 1787, that is, only three years before William Smith began his labours, Werner, by his work on the classification of mountains, laid the foundation of the German school of geology.[785] His influence was immense; and among his pupils we find the names of Mohs, Raumer, and Von Buch, and even that of Alexander Humboldt.[786] But the geological theory which he propounded, depended entirely on a chain of argument from cause to effect. He assumed, that all the great changes through which the earth had passed, were due to the action of water. Taking this for granted, he reasoned deductively from premisses with which his knowledge of water supplied him. Without entering into details respecting his system, it is enough to say, that, according to it, there was originally one vast and primeval sea, which, in the course of time, deposited the primitive rocks. The base of all was granite; then gneiss; and others followed in their order. In the bosom of the water, which at first was tranquil, agitations gradually arose, which, destroying part of the earliest deposits, gave birth to new rocks, formed out of their ruins. The stratified thus succeeded to the unstratified, and something like variety was established. Then came another period, in which the face of the waters, instead of being merely agitated, was convulsed by tempests, and, amid their play and collision, life was generated, and plants and animals sprung into existence. The vast solitude was slowly peopled, the sea gradually retired; and a foundation was laid for that epoch, during which man entered the scene, bringing with him the rudiments of order and of social improvement.[787]

These were the leading views of a system which, we must remember, exercised great sway in the scientific world, and won over to its side minds of considerable power. Erroneous and far-fetched though it was, it had the merit of calling attention to one of the two chief principles which have determined the present condition of our planet. It had the further merit of provoking a controversy, which was eminently serviceable to the interests of truth. For, the great enemy of knowledge is not error, but inertness. All that we want is discussion, and then we are sure to do well, no matter what our blunders may be. One error conflicts with another; each destroys its opponent, and truth is evolved. This is the course of the human mind, and it is from this point of view that the authors of new ideas, the proposers of new contrivances, and the originators of new heresies, are benefactors of their species. Whether they are right or wrong, is the least part of the question. They tend to excite the mind; they open up the faculties; they stimulate us to fresh inquiry; they place old subjects under new aspects; they disturb the public sloth; and they interrupt, rudely, but with most salutary effect, that love of routine, which, by inducing men to go grovelling on in the ways of their ancestors, stands in the path of every improvement, as a constant, an outlying, and, too often, a fatal obstacle.

The method adopted by Werner was evidently deductive, since he argued from a supposed cause, and reasoned from it to the effects. In that cause, he found his major premiss, and thence he worked downwards to his conclusion, until he reached the world of sense and of reality. He trusted in his one great idea, and he handled that idea with consummate skill. On that very account, did he pay less attention to existing facts. Had he chosen, he, like other men, could have collected them, and subjected them to an inductive generalization. But he preferred the opposite path. To reproach him with this is irrational; for, in his journey after truth, he chose one of the only two roads which are open to the human mind. In England, indeed, we are apt to take for granted that one road is infinitely preferable to the other. It may be so; but on this, as on many other subjects, assertions are current which have never been proved. At all events, Werner was so satisfied with his method, that he would not be at the pains of examining the position of rocks and their strata, as they are variously exhibited in different countries; he did not even explore his own country, but, confining himself to a corner of Germany, he began and completed his celebrated system, without investigating the facts on which, according to the inductive method, that system should have been built.[788]

Exactly the same process, on the same subject, and at the same time, was going on in Scotland. Hutton, who was the founder of Scotch geology, and who, in 1788, published his Theory of the Earth, conducted the inquiry just as Werner did; though, when he began his speculations, he had no knowledge of what Werner was doing.[789] The only difference between them was, that while Werner reasoned from the agency of water, Hutton reasoned from the agency of fire. The cause of this may, I think, be explained. Hutton lived in a country where some of the most important laws of heat had, for the first time, been generalized, and where consequently, that department of inorganic physics had acquired great reputation. It was natural for a Scotchman to take more than ordinary interest in a subject in which Scotland had been so successful, and had obtained so much fame. We need not, therefore, wonder that Hutton, who, like all men, felt the intellectual bent of the time in which he lived, should have yielded to an influence of which he was, perhaps, unconscious. In obedience to the general mental habits of his country he adopted the deductive method. In further obedience to the more special circumstances connected with his own immediate pursuits, he gathered the principles from which he reasoned from a study of fire, instead of gathering them, as Werner did, from a study of water.

Hence it is, that, in the history of geology, the followers of Werner are known as Neptunists, and those of Hutton as Plutonists.[790] And these terms represent the only difference between the two great masters. In the most important points, namely their method, they were entirely agreed. Both were essentially one-sided; both paid a too exclusive attention to one of the two principal agents which have altered, and are still altering, the crust of the earth; both reasoned from those agents, instead of reasoning to them; and both constructed their system without sufficiently studying the actual and existing facts; committing, in this respect, an error which the English geologists were the first to rectify.

As I am writing a history, not of science, but of scientific method, I can only briefly glance at the nature of those services which Hutton rendered to geology, and which are so considerable, that his system has been called its present basis.[791] This, however, is too strongly expressed; for, though Hutton was far from denying the influence of water,[792] he did not concede enough to it, and there is a tendency among several geologists to admit that the system of Werner considered as an aqueous theory, contains a larger amount of truth than the advocates of the igneous theory are willing to allow. Still, what Hutton did was most remarkable, especially in reference to what are now termed metamorphic rocks, the theory of whose formation he was the first to conceive.[793] Into this, and into their connexion, on the one hand, with the sedimentary rocks, and, on the other hand, with those rocks whose origin is perhaps purely igneous, I could not enter without treading on debatable ground. But, putting aside what is yet uncertain, I will mention two circumstances respecting Hutton which are undisputed, and which will give some idea of his method, and of the turn of his mind. The first circumstance is, that, although he ascribed to subterranean heat, as exhibited in volcanic action, a greater and more constant energy than any previous inquirers had ventured to do,[794] he preferred speculating on the probable consequences of that action, rather than drawing inferences from the facts which the action presented; he being on this point so indifferent, that he arrived at his conclusions without inspecting even a single region of active volcanoes, where he might have watched the workings of nature, and seen what she was really about.[795] The other circumstance is equally characteristic. Hutton, in his speculations concerning the geological effects of heat, naturally availed himself of the laws which Black had unfolded. One of those laws was, that certain earths owe their fusibility to the presence of fixed air in them before heat has expelled it; so that if it were possible to force them to retain their fixed air, or carbonic acid gas, as we now call it, no amount of heat could deprive them of the capability of being fused. The fertile mind of Hutton saw, in this discovery, a principle from which he could construct a geological argument. It occurred to him, that great pressure would prevent the escape of fixed air from heated rocks, and would thus enable them to be fused, notwithstanding their elevated temperature. He then supposed that, at a period anterior to the existence of man, such a process had taken place under the surface of the sea, and that the weight of so great a column of water had prevented the rocks from being decomposed while they were subjected to the action of fire. In this way, their volatile parts were held together, and they themselves might be melted, which could not have happened except for this enormous pressure. By following this line of argument, he accounted for the consolidation of strata by heat; since, according to the premisses from which he started, the oily, or bituminous parts, would remain, in spite of the efforts of heat to disperse them.[796] This striking speculation led to the inference, that the volatile components of a substance, and its fixed components, may be made to cohere, in the very teeth of that apparently irresistible agent whose business it is to effect their separation. Such an inference was contrary to all experience; or, to say the least, no man had ever seen an instance of it.[797] Indeed, the event was only supposed to happen in consequence of circumstances which were never met with on the surface of the globe, and which, therefore, were out of the range of all human observation.[798] The utmost that could be expected was, that, by means of our instruments, we might, perhaps, on a small scale, imitate the process which Hutton had imagined. It was possible, that a direct experiment might artificially combine great pressure with great heat, and that the result might be, that the senses would realize what the intellect had conceived.[799] But the experiment had never been tried, and Hutton, who delighted in reasoning from ideas rather than from facts, was not likely to undertake it.[800] He cast his speculation on the world, and left it to its fate.[801] Fortunately, however, for the reception of his system, a very ingenious and skilful experimenter of that day, Sir James Hall, determined to test the speculation by an appeal to facts; and as nature did not supply the facts which he wanted, he created them for himself. He applied heat to powdered chalk, while, at the same time, with great delicacy of manipulation, he subjected the chalk to a pressure about equal to the weight of a column of water half a mile high. The result was, that, under that pressure, the volatile parts of the chalk were held together; the carbonic acid gas was unable to escape; the generation of quicklime was stopped; the ordinary operations of nature were baffled, and the whole composition, being preserved in its integrity, was fused, and, on subsequently cooling, actually crystallized into solid marble.[802] Never was triumph more complete. Never did a fact more fully confirm an idea.[803] But, in the mind of Hutton, the idea preceded the fact by a long interval; since, before the fact was known, the theory had been raised, and the system which was built upon it had, indeed, been published several years. It, therefore, appears that one of the chief parts of the Huttonian Theory, and certainly its most successful part, was conceived in opposition to all preceding experience; that it pre-supposed a combination of events which no one had ever observed, and the mere possibility of which nothing but artificial experiment could prove; and, finally, that Hutton was so confident of the validity of his own method of inquiry, that he disdained to make the experiment himself, but left to another mind that empirical branch of the investigation which he deemed of little moment, but which we, in England, are taught to believe is the only safe foundation of physical research.[804]

I have now given an account of all the most important discoveries made by Scotland, in the eighteenth century, respecting the laws of the inorganic world. I have said nothing of Watt, because, although the steam-engine, which we owe to him, is of incalculable importance, it is not a discovery, but an invention. An invention it may justly be termed, rather than an improvement.[805] Notwithstanding what had been effected in the seventeenth century, by De Caus, Worcester, Papin, and Savery, and notwithstanding the later additions of Newcomen and others, the real originality of Watt is unimpeachable. His engine was, essentially, a new invention; but, under its scientific aspect, it was merely a skilful adaptation of laws previously known; and one of its most important points, namely, the economy of heat, was a practical application of ideas promulgated by Black.[806] The only discovery made by Watt, was that of the composition of water. Though his claims are disputed by the friends of Cavendish, it would appear that he was the first who ascertained that water, instead of being an element, is a compound of two gases.[807] This discovery was a considerable step in the history of chemical analysis, but it neither involved nor suggested any new law of nature, and has, therefore, no claim to mark an epoch in the history of the human mind.[808] There is, however, one circumstance connected with it which is too characteristic to be passed over in silence. The discovery was made in 1783, by Watt, the Scotchman, and by Cavendish, the Englishman, neither of whom seems to have been aware of what the other was doing.[809] But between the two there was this difference. Watt, for several years previously, had been speculating on the subject of water in connexion with air, and having, by Black's law of latent heat, associated them together, he was prepared to believe that one is convertible into the other.[810] The idea of an intimate analogy between the two bodies having once entered his mind, gradually ripened; and when he, at last, completed the discovery, it was merely by reasoning from data which others possessed besides himself. Instead of bringing to light new facts, he drew new conclusions from former ideas.[811] Cavendish, on the other hand, obtained his result by the method natural to an Englishman. He did not venture to draw a fresh inference, until he had first ascertained some fresh facts. Indeed, his discovery was so completely an induction from his own experiments, that he omitted to take into consideration the theory of latent heat, from which Watt had reasoned, and where that eminent Scotchman had found the premisses of his argument.[812] Both of these great inquirers arrived at truth, but each accomplished his journey by a different path. And this antithesis is accurately expressed by one of the most celebrated of living chemists, who, in his remarks on the composition of water, truly says, that while Cavendish established the facts, Watt established the idea.[813]

Thus much, as to what was effected by the Scotch in the department of inorganic science. If we now turn to organic science, we shall find that, there also, their labours were very remarkable. To those who are capable of a certain elevation and compass of thought, it will appear, in the highest degree, probable, that, between the organic and inorganic world, there is no real difference. That they are separated, as is commonly asserted, by a sharp line of demarcation, which indicates where one abruptly ends, and the other abruptly begins, seems to be a supposition altogether untenable. Nature does not pause, and break off in this fitful and irregular manner. In her works there is neither gap nor chasm. To a really scientific mind, the material world presents one vast and uninterrupted series, gradually rising from the lowest to the highest forms, but never stopping. In one part of that series, we find a particular structure, which, so far as our observations have yet extended, we, in another part, cannot find. We also observe particular functions, which correspond to the structure, and, as we believe, result from it. This is all we know. Yet, from these scanty facts, we, who, at present, are still in the infancy of knowledge, and have but skimmed the surface of things, are expected to infer, that there must be a point, in the chain of existence, where both structure and function suddenly cease, and, after which, we may vainly search for signs of life. It would be difficult to conceive a conclusion more repugnant to the whole march and analogy of modern thought. In every department, the speculations of the greatest thinkers are constantly tending to coÖrdinate all phenomena, and to regard them as different, indeed, in degree, but by no means as different in kind. Formerly, men were content to ground their conviction of this difference in kind, on the evidence of the eye, which, on a cursory inspection, saw an organization in some bodies, and not in others. From the organization, they inferred the life, and supposed that plants, for instance, had life, but that minerals had none. This sort of argument was long deemed satisfactory; but, in the course of time, it broke down; more evidence was required, and, since the middle of the seventeenth century, it has been universally admitted, that the eye, by itself, is an untrustworthy witness, and that we must employ the microscope, instead of relying on the unaided testimony of our own puny and precarious senses. But the microscope is steadily improving, and we cannot tell what limits there are to its capacity for improvement. Consequently, we cannot tell what fresh secrets it may disclose. Neither can we say, that it may not be altogether superseded by some new artificial resource, which shall furnish us with evidence, as superior to any yet supplied, as our present evidence is superior to that of the naked eye. Even already, and notwithstanding the shortness of time during which the microscope has been a really effective instrument, it has revealed to us organizations, the existence of which no one had previously suspected. It has proved, that what, for thousands of years, had been deemed mere specks of inert matter, are, in truth, animals possessing most of the functions which we possess, reproducing their species in regular and orderly succession, and endowed with a nervous system, which shows that they must be susceptible of pain and enjoyment. It has detected life hidden in the glaciers of Switzerland; it has found it embedded in the polar ice, and, if it can flourish there, it is hard to say from what quarter it can be shut out. So unwilling, however, are most men to relinquish old notions, that the resources of chemistry have been called in, to ascertain the supposed difference between organic and inorganic matter: it being asserted, that, in the organic world, there is a greater complexity of molecular combination, than in the inorganic.[814] Chemists further assert, that, in organic nature, there is a predominance of carbon, and, in inorganic, a predominance of silicon.[815] But chemical analysis, like microscopic observation, is making such rapid strides, that each generation, I had almost said each year, is unsettling some of the conclusions previously established; so that, now, and for a long time hence, we must regard those conclusions as empirical, and, indeed, as merely tentative. Surely a permanent and universal inference cannot be drawn from shifting and precarious facts, which are admitted to-day, and may be overthrown to-morrow. It would, therefore, appear that, in favour of the opinion, that some bodies are living, and that others are dead, we have nothing, except the circumstance, that our researches, so far as they have yet gone, have shown that cellular structure, growth, and reproduction, are not the invariable properties of matter, but are excluded from a large part of the visible world, which, on that account, we call inanimate. This is the whole of the argument on that side of the question. On the other side, we have the fact, that our sight, and the artificial instruments, by whose aid we have arrived at this conclusion, are confessedly imperfect; and we have the further fact, that, imperfect as they are, they have proved, that the organic kingdom is infinitely more extensive than the boldest dreamer had ever imagined, while they have not been able to enlarge the boundaries of the inorganic kingdom to any thing like the same amount. This shows, that, so far as our opinions are concerned, the balance is steadily inclining in one given direction; in other words, as our knowledge advances, a belief in the organic is encroaching upon a belief in the inorganic.[816] When we, moreover, add, that all science is manifestly converging towards one simple and general theory, which shall cover the whole range of material phenomena, and that, at each successive step, some irregularities are explained away, and some inequalities are reduced, it can hardly be doubted, that such a movement tends to weaken those old distinctions, the reality of which has been too hastily assumed; and that, in their place, we must, sooner or later, substitute the more comprehensive view, that life is a property of all matter, and that the classification of bodies into animate and inanimate, or into organic and inorganic, is merely a provisional arrangement, convenient, perhaps, for our present purposes, but which, like all similar divisions, will eventually be merged in a higher and wider scheme.

Until, however, that step is taken, we must be content to reason according to the evidence supplied by our imperfect instruments, or by our still more imperfect senses. We, therefore, recognize the difference between organic and inorganic nature, not as a scientific truth, but as a scientific artifice, by which we separate in idea, what is inseparable in fact; hoping, in this way, to pursue our course with the greater ease, and ultimately to obtain results, which will make the artifice needless. Assuming, then, this division, we may refer all investigations of organic bodies to one of two objects. The first object is, to ascertain the law of those bodies, in their usual, healthy, or, as we somewhat erroneously phrase it, normal course. The other object is, to ascertain their law, in their unusual, unhealthy, or abnormal course. When we attempt to do the first of these things, we are physiologists. When we attempt to do the second, we are pathologists.[817]

Physiology and pathology are thus the two fundamental divisions of all organic science.[818] Each is intimately connected with the other; and eventually, no doubt, both will be fused into a single study, by discovering laws which will prove that here, as elsewhere, nothing is really abnormal, or irregular. Hitherto, however, the physiologists have immeasurably outstripped the pathologists in the comprehensiveness of their views, and, therefore, in the value of their results. For, the best physiologists distinctly recognize that the basis of their science must include, not only the animals below man, but also the entire vegetable kingdom, and that, without this commanding survey of the whole realm of organic nature, we cannot possibly understand even human physiology, still less general physiology. The pathologists, on the other hand, are so much in arrear, that the diseases of the lower animals rarely form part of their plan; while the diseases of plants are almost entirely neglected, although it is certain that, until all these have been studied, and some steps taken to generalize them, every pathological conclusion will be eminently empirical, on account of the narrowness of the field from which it is collected.

The science of pathology being still so backward in the conception as well as in the execution, that even men of real ability believe that it can be raised from a mere study of the human frame, it will hardly be expected that the Scotch, notwithstanding the marvellous boldness of their speculations, should have been able, in the eighteenth century, to anticipate a method which the nineteenth century has yet to employ. But they produced two pathologists of great ability, and to whom we owe considerable obligations. These were, Cullen and John Hunter.[819] Cullen was eminent only as a pathologist; but Hunter, whose fine and discursive genius took a much wider range, was great both in physiology and in pathology. A short account of their generalizations respecting organic science, will be a fitting sequel to the notices I have already given of what was done by their countrymen for inorganic science, during the same period. It will complete our survey of the Scotch intellect, and will enable the reader to form some idea of the brilliant achievements of that most remarkable people, who, contrary to the course of affairs in all other modern nations, have shown that scientific discoveries do not necessarily weaken superstition, and that it is possible for two hostile principles to flourish side by side, without ever coming into actual collision, or without sensibly impairing each other's vigour.

In 1751, Cullen was appointed professor of medicine in the University of Glasgow;[820] from which, however, in 1756, he was removed to the University of Edinburgh,[821] where he delivered those celebrated lectures, on which his fame now depends. During the early part of his career, he paid great attention to inorganic physics, and propounded some remarkable speculations, which are supposed to have suggested the theory of latent heat to Black, who was his pupil.[822] But, to follow out those views, would have required a number of minute experiments, which it did not suit the habit of his mind to make. Having, therefore, put forth his ideas, he left them to germinate, and passed on to his arduous attempt to generalize the laws of disease as they are exhibited in the human frame. In the study of disease, the phenomena being more obscure and less amenable to experiment, there was greater latitude for speculation; hence, he could more easily indulge in that love of theory, which was his ruling passion, and with an extreme devotion to which he has been reproached.[823] That the reproach is not altogether unjust, must, I think, be admitted, since we find him laying down the doctrine, that, inasmuch as, in the treatment of disease, theory could not be separated from practice, it was unimportant which came first.[824] This was tantamount to saying, that a medical practitioner might allow his theories to control his observations; for it is certain that, in an immense majority of cases, men are so tenacious of the opinions they imbibe, that whatever, in any pursuit, first occupies their understanding, is likely to mould all that comes afterwards. In ordinary minds, associations of ideas, if firmly established, become indissoluble; and the power of separating them, and of arranging them in new combinations, is one of the rarest of our endowments. An average intellect, when once possessed by a theory, can hardly ever escape from it. Hence, in practical matters, theory should be feared, just as, in scientific matters, it should be cherished; because practical pursuits are chiefly engrossed by the lower class of minds, where associations and the force of prejudice are extremely strong, while scientific pursuits concern the higher class, where such prepossessions are comparatively weak, and where close associations are more easily severed. The most powerful intellects are most accustomed to new arrangements of thought, and are, therefore, most able to break up old ones. On them, belief sits lightly, because they well know how little evidence we have for many of even our oldest beliefs. But the average, or, as we must say, without meaning offence, the inferior, minds, are not disturbed by these refinements. Theories, which they have once heartily embraced, they can hardly ever get rid of, and they often dignify them with the name of essential truths, and resent every attack upon them as a personal injury. Having inherited such theories from their fathers, they regard them with a sort of filial piety, and cling to them as if they were some rich acquisition, which no one has a right to touch.

To this latter class, nearly all men belong, who are more engaged in practical pursuits than in speculative ones. Among them, are the ordinary practitioners, whether in medicine or in any other department, extremely few of whom are willing to break up trains of thought to which they are inured.[825] Though they profess to despise theory, they are, in reality, enslaved by it. All that they can do, is to conceal their subjection, by terming their theory a necessary belief. It must, therefore, be deemed a remarkable proof of Cullen's love of deductive reasoning, that he, sagacious and clear-sighted as he was, should have supposed that, in so practical an art as medicine, theory could, with impunity, precede practice. For, it is most assuredly true, that, taking men in the average, their minds are so constructed, that it cannot precede it without controlling it. It is equally true, that such control must be hurtful. Even now, and notwithstanding the great steps which have been taken in morbid anatomy, in animal chemistry, and in the microscopic investigation both of the fluids and solids of the human frame, the treatment of disease is a question of art, far more than a question of science. What chiefly characterizes the most eminent physicians, and gives them their real superiority, is not so much the extent of their theoretical knowledge,—though that, too, is often considerable,—but it is that fine and delicate perception which they owe, partly to experience, and partly to a natural quickness in detecting analogies and differences which escape ordinary observers. The process which they follow, is one of rapid, and, in some degree, unconscious, induction. And this is the reason why the greatest physiologists and chemists, which the medical profession possesses, are not, as a matter of course, the best curers of disease. If medicine were a science, they would always be the best. But medicine, being still essentially an art, depends mainly upon qualities which each practitioner has to acquire for himself, and which no scientific theory can teach. The time for a general theory has not yet come, and probably many generations will have to elapse before it does come. To suppose, therefore, that a theory of disease should, as a matter of education, precede the treatment of disease, is not only practically dangerous, but logically false. With its practical danger I am not now concerned; but its logical aspect is a curious illustration of that passion for systematic and dialectic reasoning which characterized Scotland. It shows that Cullen, in his eagerness to argue from principles to facts, instead of from facts to principles, could, in the most important of all arts, recommend a method of procedure, for which even our knowledge is not ripe, but which, in his time, was so singularly rash and immature, that nothing can explain its adoption by a man of such vigorous understanding, except the circumstance of his living in a country in which that peculiar method reigned supreme.

It must, however, be admitted that Cullen wielded the method with great ability, especially in his application of it to the science of pathology, to which it was far better suited than to the art of therapeutics. For, we must always remember, that the science which investigates the laws of disease, is quite a different thing from the art which cures it. The science has a speculative interest, which is irrespective of all practical considerations, and which depends simply on the fact, that, when it is completed, it will explain the aberrations of the whole organic world. Pathology aims at ascertaining the causes which determine every departure from the natural type, whether of form or of function. Hence it is, that no one can take a comprehensive view of the actual state of knowledge, without studying the theoretic relations between pathology and other departments of inquiry. To do this, is the business, not of practical men, but of philosophers, properly so called. The philosophic pathologist is as different from the physician, as a jurist is different from an advocate, or as an agricultural chemist is different from a farmer, or as a political economist is different from a statesman, or as an astronomer, who generalizes the laws of the heavenly bodies, is different from a captain, who navigates his ship by a practical application of those laws. The two sets of functions may be united, and occasionally, though very rarely, they are, but there is no necessity for their being so. While, therefore, it would be absurdly presumptuous for an unprofessional person to pass judgment on the therapeutical system of Cullen, it is perfectly legitimate for any one, who has studied the theory of these matters, to examine his pathological system; because that, like all scientific systems, must be amenable to general considerations, which are to be taken, partly from the adjoining sciences, and partly from the universal logic of philosophic method.

It is from this latter, or logical, point of view, that Cullen's pathology is interesting for the purposes of the present chapter. The character of his investigations may be illustrated by saying, that his method in pathology is analogous to that which Adam Smith adopted at the same time, though in a very different field. Both were deductive; and both, before arguing deductively, suppressed some of the premisses from which they reasoned. That this suppression is the key to Adam Smith's method, and was an intentional part of his plan, I have already shown; as also that, in each of his two works, he supplied the premisses in which the other work was deficient. In this respect, he was far superior to Cullen. For, though Cullen, like Smith, began by mutilating his problem in order to solve it more readily, he, unlike Smith, did not see the necessity of instituting another and parallel inquiry, which should complete the scheme, by starting from the premisses that had been previously omitted.

What I have termed the mutilation of the problem, was effected by Cullen in the following manner. His object was, to generalize the phenomena of disease, as they are exhibited in the human frame; and it was obvious to him, as to every one else, that the human frame consists partly of solids and partly of fluids. The peculiarity of his pathology is, that he reasons almost entirely from the laws of the solids, and makes so little account of the fluids, that he will only allow them to be the indirect causes of disease, which, in a scientific view, are to be deemed strictly subordinate to the direct causes, as represented by the solid constituents of our body.[826] This assumption, though false, was perfectly justifiable, since, by curtailing the problem, he simplified its study; just as Adam Smith, in his Wealth of Nations, simplified the study of human nature, by curtailing it of all its sympathy. But this most comprehensive thinker was careful, in his Theory of Moral Sentiments, to restore to human nature the quality of which the Wealth of Nations had deprived it; and, by thus establishing two different lines of argument, he embraced the whole subject. In the same way, it was incumbent on Cullen, after having constructed a theory of disease by reasoning from the solids, to have constructed another theory by reasoning from the fluids; so that a coÖrdination of the two theories might have raised a science of pathology, as complete as the then state of knowledge allowed.[827] But to this, his mind was unequal. Able though he was, he lacked the grasp of intellect which characterized Adam Smith, and which made that great man perceive, that every deductive argument which is founded on a suppression of premisses, must be compensated by a parallel argument, which takes those premisses into account.[828] So little was Cullen aware of this, that, having built up that system of pathology which is known to medical writers as Solidism, he never took the pains to accompany it by another system, which gave the first rank to the fluids. On the contrary, he believed that his plan was complete and exhaustive, and that what is termed Humoral Pathology was a fiction, which had too long usurped the place of truth.[829]

Several of the views advocated by Cullen were taken from Hoffmann, and several of the facts from Gaubius; but that his pathology, considered as a whole, is essentially original, is evident from a certain unity of design which is inconsistent with extensive plagiarism, and which proves that he had thoroughly thought out his subject for himself. Without, however, stopping to inquire how much he borrowed from others, I will briefly indicate a few of the salient points of his system, in order to enable the reader to understand its general character.

According to Cullen, all the solids in the human body are either simple or vital. The simple solids retain, after death, the properties which they possessed during life. But the vital solids, which form the fundamental part of the nervous system, are marked by properties, which disappear directly death occurs.[830] Hence, the simple solids, having fewer functions than the vital, have also fewer diseases; and the maladies to which they are liable admit of easy classification.[831] The real difficulty lies in the vital solids, because on their peculiarities the whole nervous system depends, and nearly all disorders are immediately due to changes in them. Cullen, therefore, made the nervous system the basis of his pathology; and, in speculating on its functions, he assigned the chief place to an occult principle, which he termed the Animal Power, or Energy, of the brain.[832] This principle acted on the vital solids. When the principle worked well, the body was healthy; when it worked ill, the body was unhealthy. Since, then, the state of the vital solids was the main cause of disorder, and since the Energy of the brain was the main cause of the state of the vital solids, it became important to know what the influences were which acted on the Energy, because in them we should find the beginning of the series. Those influences were divided by Cullen into physical and mental. The physical were, heat, cold, and effluvia, the three most potent of the material disturbers of the human frame.[833] The mental influences, which excited the brain to act on the solids, were comprised under six different heads, namely, the will, the emotions, the appetites, the propensities, and, finally, the two great principles of habit and of imitation, on which he, with good reason, laid considerable stress.[834] In arguing from these mental causes, and in generalizing the relations between them and the sensations of the body, he, faithful to his favourite method, proceeded deductively from the metaphysical principles then in vogue, without inquiring inductively into their validity, such an induction being, he thought, no part of his duty.[835] He was too anxious to get on with his dialectic, to be interrupted by so trifling a matter as the truth or falsehood of the premisses on which the reason rested. What he did in the metaphysical part of his pathology, he also did in its physical part. Although the blood and the nerves are the two leading features of the human economy, he did not search into them by a separate induction; he subjected them neither to chemical experiments in order to learn their composition, nor to microscopic observations in order to learn their structure.[836] This is the more observable, because though we must admit that animal chemistry was then generally neglected, and that its real meaning was scarcely understood until the wonderful labours of Berzelius revealed its importance, still the microscope was ready to Cullen's hands; it having been invented a hundred and fifty years before he completed his pathology, and having been in common scientific use for about a hundred years. But his love of synthesis overcame him. His system is constructed by reasoning from general principles; and of that process, he certainly was a consummate master. Between the premisses and the conclusion, he hardly ever lets error creep in. And, in reference to the results of his speculations, he had one immense merit, which will always secure to him a conspicuous place in the history of pathology. By insisting on the importance of the solids, he, one-sided though he was, corrected the equal one-sidedness of his predecessors; for, with extremely few exceptions, all the best pathologists, from Galen downwards, had erred in ascribing too much to the fluids, and had upheld a purely humoral pathology. Cullen turned the minds of men in the other direction; and though, in teaching them that the nervous system is the sole primary seat of disease, he committed a great mistake, it was a mistake of the most salutary kind. By leaning on that side, he restored the balance. Hence, I have no doubt, he indirectly encouraged those minute researches into the nerves, which he would not himself stop to make, but which, in the next generation, gave rise to the capital discoveries of Bell, Shaw, Mayo, and Marshall Hall. At the same time, the old humoral pathology, which had prevailed for many centuries, was practically pernicious, because, assuming that all diseases are in the blood, it produced that constant and indiscriminate venesection, which destroyed innumerable lives, besides the irreparable injury it often inflicted both on body and mind; weakening those whom it was unable to slay. Against this merciless onslaught, which made medicine the curse of mankind, the Solid Pathology was the first effective barrier.[837] Practically, therefore, as well as speculatively, we must hail Cullen as a great benefactor of his species; and we must regard his appearance as an epoch in the history of human comfort, as well as in the history of human thought.

It may, perhaps, facilitate the conceptions of unprofessional readers, if I give, in as few words as possible, a specimen of the way in which Cullen employed his method, in investigating the theory of some one class of diseases. For this purpose, I will select his doctrine of fever, which, though now generally abandoned, once exercised more influence than any other part of his pathology. Here, as elsewhere, he reasons from the solids.[838] Disregarding the state of the blood, he says, that the cause of all fever is a diminished energy of the brain.[839] Such diminution may be produced by various sedatives, the most common of which are effluvia, whether marsh or human, intemperance, fear, and cold.[840] Directly the energy of the brain is impaired, the disease begins. Rapidly passing through the nervous system, its first palpable effect is a chill, or cold fit, which is accompanied by a spasm on the extremities of the arteries, particularly where they touch the surface of the body.[841] This spasm on the extreme vessels, irritates the heart and arteries, and the irritation continues till the spasm is relaxed.[842] At the same time, the increased action of the heart restores the energy of the brain; the system rallies; the extreme vessels are relieved; while, as a consequence of the whole movement, sweat is excreted, and the fever abates.[843] Shutting out, therefore, all consideration of the fluids of the body, the successive stages of languor, cold fit, and hot fit, might, in Cullen's opinion, be generalized by reasoning merely from the solids, which, furthermore, produced his well-known distinction between fevers, the continuance of which is owing to an excess of spasm, and those, the continuance of which is owing to an excess of debility.[844]

A similar process of thought gave birth to his Nosology, or general classification of diseases, which some have regarded as the most valuable part of his labours;[845] though, for reasons already mentioned, we must, I think, reject all such attempts as premature, and as likely to work more harm than good, unless they are simply used as a contrivance to aid the memory. At all events, the Nosology of Cullen, though it exhibits clear traces of his powerful and organizing mind, is fast falling into disrepute, and we may be sure, that, for a long time yet, a similar fate will await its successors. Our pathological knowledge is still too young for so great an enterprise.[846] We have every reason to expect, that, with the aid of chemistry, and of the microscope, it will continue to grow more rapidly than it has hitherto done. Without venturing to predict the rate of its increase, we may form some idea of it, by considering what has been effected with resources very inferior to those we now possess. In a work of great authority, published in the year 1848, it is stated, that since the appearance of Cullen's Nosology, our mere enumeration of diseases has almost doubled, while our knowledge of the facts relating to disease has more than doubled.[847]

I have now only one more name to add to this splendid catalogue of the great Scotchmen of the eighteenth century.[848] But it is the name of a man, who, for comprehensive and original genius, comes immediately after Adam Smith, and must be placed far above any other philosopher whom Scotland has produced. I mean, of course, John Hunter, whose only fault was, an occasional obscurity, not merely of language, but also of thought. In this respect, and, perhaps, in this alone, Adam Smith had the advantage; for his mind was so flexible, and moved so freely, that even the vastest designs were unable to oppress it. With Hunter, on the contrary, it sometimes seemed as if the understanding was troubled by the grandeur of his own conceptions, and doubted what path it ought to take. He hesitated; the utterance of his intellect was indistinct.[849] Still, his powers were so extraordinary, that, among the great masters of organic science, he belongs, I apprehend, to the same rank as Aristotle, Harvey, and Bichat, and is somewhat superior either to Haller or Cuvier. As to this classification, men will differ, according to their different ideas of the nature of science, and, above all, according to the extent to which they appreciate the importance of philosophic method. It is from this latter point of view that I have, at present, to consider the character of John Hunter; and, in tracing the movements of his most remarkable mind, we shall find, that, in it, deduction and induction were more intimately united than in any other Scotch intellect, either of the seventeenth or eighteenth century. The causes of this unusual combination, I will now endeavour to ascertain. When they are understood, they will not only explain many peculiarities in his works, but will afford materials for speculation, to those who love to examine the development of ideas, and who are able to discern the way in which different schemes of national thought have given different shapes to national character, and have thereby modified the whole course of human affairs, to an extent of which the ordinary compilers of history have not the slightest suspicion.

Hunter remained in Scotland till the age of twenty, when he settled in London; and, though he was abroad for about three years, he abandoned his own country, and became, socially and intellectually, a native of England.[850] Hence, the early associations of his mind were formed in the midst of a deductive nation; the later associations, in the midst of an inductive one. For twenty years he lived among a people, who are, perhaps, the acutest reasoners in Europe, if you concede to them the principles from which they reason; but who, on the other hand, owing to their proneness to this method, are so greedy after general principles, that they will accept them on almost any evidence, and are, therefore, at once very credulous and very logical. In that school, and surrounded by those habits, the intellect of John Hunter was nurtured during the most impressible period of his life. Then the scene suddenly shifted. Coming to England, he passed forty years in the heart of the most empirical nation in Europe; a nation utterly abhorring all general principles, priding itself on its common sense, boasting, and with good reason too, of its practical sagacity, proclaiming aloud the superiority of facts over ideas, and despising every theory, unless some direct and immediate benefit could be expected to accrue from it. The young and ardent Scotchman found himself transplanted into a country totally different from that which he had just quitted; and such a difference could not fail to influence his mind. He saw, on every side, marks of prosperity, and of long and uninterrupted success, not only in practical, but also in speculative, life; and he was told that these things were effected by a system which made facts the first consideration. He was ambitious of fame, but he perceived that the road to fame was not the same in England as in Scotland. In Scotland, a great logician would be deemed a great man; in England, little account would be made of the beauty of his logic, unless he was careful that the premisses from which he argued, were trustworthy, and verified by experience. A new machine, a new experiment, the discovery of a salt, or of a bone, would, in England, receive a wider homage, than the most profound speculation from which no obvious results were apprehended. That this way of contemplating affairs has produced great good, is certain. But it is also certain, that it is a one-sided way, and satisfies only part of the human mind. Many of the noblest intellects crave for something which it cannot supply. In England, however, during the greater part of the eighteenth century, it was even more supreme than it is now, and was, indeed, so universal, that, from the year 1727 until nearly the close of the century, our country did not possess, in any branch of science, a speculator who had sufficient force to raise himself above those narrow views which were then deemed the perfection of wisdom.[851] Much was added to our knowledge, but its distant boundaries were not enlarged. Though there was an increase of curious and valuable details, and though several of the small and proximate laws of nature were generalized, it must be admitted, that those lofty generalizations, which we owe to the seventeenth century, remained stationary, and that no attempt was made to push beyond them. When John Hunter arrived in London, in 1748, Newton had been dead more than twenty years, and the English people, absorbed in practical pursuits, and now beginning, for the first time, to enter into political life, had become more averse than ever to inquiries which aimed at truth without regard to utility, and had accustomed themselves to value science chiefly for the sake of the direct and tangible benefit which they might hope to derive from it.

That Hunter must have been influenced by these circumstances, will be obvious to whoever considers how impossible it is for any single mind to escape from the pressure of contemporary opinion. But, inasmuch as all his early associations had inclined him in another direction, we perceive that, during his long residence in England, he was acted on by two conflicting forces. The country of his birth made him deductive; the country of his adoption made him inductive. As a Scotchman, he preferred reasoning from general principles to particular facts; as an inhabitant of England, he became inured to the opposite plan of reasoning from particular facts to general principles. In every country, men naturally give the first place to what is most valued. The English respect facts more than principles, and therefore begin with the facts. The Scotch consider principles as most important, and therefore begin with the principles. And, I make no doubt that one of the reasons why Hunter, in investigating a subject, is often obscure, is that, on such occasions, his mind was divided between these two hostile methods, and that, leaning sometimes to one and sometimes to the other, he was unable to determine which he should choose. The conflict darkened his understanding. Adam Smith, on the other hand, in common with all the great Scotchmen who remained in Scotland, was remarkably clear. He, like Hume, Black, and Cullen, never wavered in his method. These eminent men were not acted on by English influence. Of all the most illustrious Scotchmen of the eighteenth century, Hunter alone underwent that influence, and he alone displayed a certain hesitation and perplexity of thought, which seems unnatural to so great a mind, and which, as it appears to me, is best explained by the peculiar circumstances in which he was placed.

One of the ablest of his commentators has justly observed, that his natural inclination was, to conjecture what the laws of nature were, and then reason from them, instead of reasoning to them by slow and gradual induction.[852] This process of deduction was, as I have shown, the favourite method of all Scotchmen, and, therefore, was precisely the course which we should have expected him to adopt. But, inasmuch as he was surrounded by the followers of Bacon,[853] this natural bias was warped, and a large part of his marvellous activity was employed in observations and experiments, such as no Scotch thinker, living in Scotland, would ever have engaged in. He himself declared, that thinking was his delight;[854] and there can be no doubt that, had he been differently situated, thinking would have been his principal pursuit. As it was, the industry with which he collected facts, is one of the most conspicuous features in his career. His researches covered the whole range of the animal kingdom, and were conducted with such untiring zeal, that he dissected upwards of five hundred different species, exclusive of dissections of different individuals, and exclusive, too, of dissections of a large number of plants.[855] The results were carefully arranged and stored up in that noble collection which he formed, and of the magnitude of which we may gain some idea from the statement, that, at his death, it contained upwards of ten thousand preparations illustrative of the phenomena of nature.[856] By this means, he became so intimately acquainted with the animal kingdom, that he made a vast number of discoveries, which, considered singly, are curious, but which, when put together, constitute an invaluable body of new truths. Of these, the most important are, the true nature of the circulation in crustacea and insects;[857] the organ of hearing in cephalopods;[858] the power possessed by mollusks of absorbing their shells;[859] the fact that bees do not collect wax, but secrete it;[860] the semicircular canals of the cetacea;[861] the lymphatics of birds;[862] and the air-cells in the bones of birds.[863] We are also assured, that he anticipated the recent discoveries respecting the embryo of the kangaroo;[864] and his published works prove, that, in the human subject, he discovered the muscularity of the arteries,[865] the muscularity of the iris,[866] and the digestion of the stomach after death by its own juice.[867] Although, in his time, animal chemistry was not yet raised to a system, and was consequently little heeded by physiologists, Hunter endeavoured, by its aid, to search out the qualities of the blood, so as to ascertain the properties of its constituents.[868] He also examined it in different stages of embryonic life, and by minutely tracking it through its periods of development, he made the capital discovery, that the red globules of the blood are formed later than its other components. His contemporaries, however, were so little alive to the importance of this great physiological truth, that it fell dead upon them, and, being forgotten, it was, about fifty years afterwards, rediscovered, and was announced, in 1832, as a law of nature which had just been brought to light.[869] This is one of many instances in the history of our knowledge, which proves how useless it is for a man to advance too far beyond the age in which he lives.[870] But Hunter, besides making the discovery, also saw its meaning. From it, he inferred that the function of the red globules is to minister to the strength of the system, rather than to its repair.[871] This is now universally admitted; but it was not admitted till long after his death. Its recognition is chiefly owing to the rapid advance of animal chemistry, and to improvements in the microscope. For, by the employment of these resources, it has become manifest, that the red globules, the respiratory process, the production of animal heat, and the energy of the locomotive organs, are but different parts of a single scheme.[872] Their connexion with each other is established, not only by a comparison of different species, but also by a comparison of different members of the same species. In human beings, for example, the locomotive and other animal functions are more active in persons of a sanguine temperament than in those of a lymphatic temperament; while, in sanguine temperaments, the globules are more numerous than in lymphatic ones. The knowledge of this fact we owe to Lecanu;[873] and to him we are also indebted for an analogous fact, corroborating the same view. He has shown, that the blood of women contains more water and fewer red globules than the blood of men;[874] so that here again we discern the relation between these globules and the energy of animal life. Inasmuch, however, as these researches were not made until many years after the death of Hunter, the coincidence between them and his speculative conclusions is a striking instance of his power of generalization, and of that unrivalled knowledge of comparative anatomy, which supplied him with materials from which, in spite of the backwardness of animal chemistry, he was able to draw an inference, which later and minuter researches have decisively verified.[875]

Having thus, by a comprehensive survey of the animal world, associated its remarkable faculty of movement with the state of its blood, Hunter turned his attention to another aspect of the question, and took into consideration the movements of the vegetable world, in the hope that, by comparing these two divisions of nature, he might detect some law, which, being common to both, should unite into one study all the principles of organic motion. Though he failed in this great undertaking, some of his generalizations are very suggestive, and well illustrate the power and grasp of his mind. Looking at the organic kingdom as a whole, he supposed that its capacity of action, both in animals and in vegetables, was of three kinds. The first kind, was the action of the individual upon the materials it already possessed; and this gave rise to growth, secretion, and other functions, in which the juice of the plant was equivalent to the blood of the animal.[876] The second kind of action had for its object to increase these materials; it was always excited by want, and its result was, to nourish and preserve the individual.[877] The third kind was entirely due to external causes, including the whole material world, all the phenomena of which were a stimulus to some kind of action.[878] By combining, in different ways, these different sources of motion, and by studying every incitement to action, first, in reference to one of the three great divisions just indicated, and, secondly, in reference to the power of action, as distinguished from the quantity of action,[879] Hunter believed that some fundamental truths might be obtained, if not by himself, at all events by his successors. For, he thought that, though animals can do many things which plants cannot, still, the immediate cause of action is in both cases the same.[880] In animals, there is more variety of motion, but in plants there is more real power. A horse is certainly far stronger than a man. Yet a small vine cannot only support, but can raise, a column of fluid five times higher than a horse can. Indeed, the power which a plant exercises of holding a leaf erect during an entire day, without pause and without fatigue, is an effort of astonishing vigour, and is one of many proofs, that a principle of compensation is at work, so that the same energy which, in the animal world, is weakened by being directed to many objects, is, in the vegetable world, strengthened by being concentrated on a few.[881]

In pursuing these speculations, which, amid much that is uncertain, contain, I firmly believe, a large amount of important, though neglected, truth, Hunter was led to consider how motion is produced by various forces, such as magnetism, electricity, gravitation, and chemical attraction.[882] This carried him into inorganic science, where, as he clearly saw, the foundation of all organic science must be laid. Just as, on the one hand, the human frame could never be successfully studied, except by the aid of principles which had been collected from an investigation of animals below man,[883] so, on the other hand, the laws of those very animals must, he said, be approached through the laws of common or inorganic matter.[884] He, therefore, aimed at nothing less than to unite all the branches of physical science, taking them in the order of their relative complexity, and proceeding from the simplest to the most intricate. With this view, he examined the structure of the mineral kingdom, and, by an extensive comparison of crystals, he sought to generalize the principles of form, in the same way as, by a comparison of animals, he sought to generalize the principles of function. And, in doing this, he took into account, not only regular crystals, but also irregular ones.[885] For, he knew that, in nature, nothing is really irregular or disorderly; though our imperfect apprehension, or rather the backwardness of our knowledge, prevents us from discerning the symmetry of the universal scheme. The beauty of the plan, and the necessity of the sequence, are not always perceptible. Hence, we are too apt to fancy that the chain is broken, because we cannot see every link in it. From this serious error, Hunter was saved by his genius, even more than by his knowledge. Being satisfied that every thing which happens in the material world, is so connected and bound up with its antecedents, as to be the inevitable result of what had previously occurred, he looked with a true philosophical eye at the strangest and most capricious shapes, because to him they had a meaning and a necessary purpose. To him, they were neither strange nor capricious. They were deviations from the natural course; but it was a fundamental tenet of his philosophy, that nature, even in the midst of her deviations, still retains her regularity.[886] Or, as he elsewhere expresses it, deviation is, under certain circumstances, part of the law of nature.[887]

To generalize such irregularities, or, in other words, to show that they are not irregularities at all, was the main object of Hunter's life, and was the noblest part of his mission. Hence, notwithstanding his vast achievements in physiology, his favourite pursuit was pathology,[888] where, the phenomena being more complex, the intellect has more play. In this great field, he studied the aberrations of structure and of function, in the vegetable, as well as in the animal, world;[889] while, for the aberrations of form, which are the external manifestations of disturbed structure, he took into consideration the appearances presented by the mineral kingdom. There, the power of crystallization is the leading feature, and there, violations of symmetry constitute the essential disorder, whether the deformity of the crystal is subsequent to its production, or whether, being the result of what happened before its production, it is an original, and, if we may so say, congenital, defect. In either case, it is a deviation from the normal type, and, as such, is analogous to the monstrosities, both of animals and of vegetables.[890] The mind of Hunter, by sweeping through this immense range of thought, attained to such commanding views of the philosophy of disease, that, in that department, he is certainly without a rival. As a physiologist, he was equalled, or perhaps excelled, by Aristotle; but as a pathologist, he stands alone, if we consider what pathology was when he found it, and what it was when he left it.[891] Since his death, the rapid advance of morbid anatomy and of chemistry has caused some of his doctrines to be modified, and some of them to be overturned. This has been the work of inferior men, wielding superior chemical and microscopical resources. To say that the successors of John Hunter are inferior to him, is no disparagement to their abilities, since he was one of those extremely rare characters who only appear at very long intervals, and who, when they do appear, remodel the fabric of knowledge. They revolutionize our modes of thought; they stir up the intellect to insurrection; they are the rebels and demagogues of science. And though the pathologists of the nineteenth century have chosen a humbler path, this must not blind us to their merits, or prevent us from being grateful for what they have done. We cannot, however, be too often reminded, that the really great men, and those who are the sole permanent benefactors of their species, are not the great experimenters, nor the great observers, nor the great readers, nor the great scholars, but the great thinkers. Thought is the creator and vivifier of all human affairs. Actions, facts, and external manifestations of every kind, often triumph for a while; but it is the progress of ideas which ultimately determines the progress of the world. Unless these are changed, every other change is superficial, and every improvement is precarious. It is, however, evident that, in the present state of our knowledge, all ideas respecting nature must refer either to the normal or to the abnormal; that is to say, they must be concerned either with what is regular, uniform, and obedient to recognized principles, or else with what is irregular, perturbed, and disobedient. Of these two divisions, the first belongs to science; the second, to superstition. John Hunter formed the superb conception of merging both classes of ideas into one, by showing that nothing is irregular, that nothing is perturbed, that nothing is disobedient. Centuries, perhaps, may elapse before that conception will be consummated. But what Hunter effected towards it, places him at the head of all pathologists, ancient or modern. For, with him, the science of pathology did not mean the laws of disease in man alone, or even in all animals, or even in the whole organic kingdom; but it meant the laws of disease and of malformation in the entire material world, organic and inorganic. His great object was, to raise a science of the abnormal. He determined to contemplate nature as a vast and united whole, exhibiting, indeed, at different times different appearances, but preserving, amidst every change, a principle of uniform and uninterrupted order, admitting of no deviation, undergoing no disturbance, and presenting no real irregularity, albeit to the common eye, irregularities abound on every side.

As pathology was the science to which Hunter was most devoted, so also was it that in which his natural love of deduction was most apparent. Here, far more than in his physiological inquiries, do we find a desire to multiply original principles from which he could reason; in opposition to the inductive method, which always aims at diminishing these principles by gradual and successive analysis. Thus, for instance, in his animal pathology, he attempted to introduce, as an ultimate principle from which he could argue, the idea that all diseases move more rapidly towards the skin than towards internal parts, by virtue of some hidden force, which also obliges vegetables to approach the surface of the earth.[892] Another favourite proposition, which he often used as a major premiss, and by its aid constructed deductively a pathological argument, was, that in no substance, be it what it may, can two processes go on in the same part at the same time.[893] By applying this universal proposition to the more limited phenomena of animal life, he inferred that two general diseases cannot co-exist in the same individual; and he relied so much on this ratiocination, that he refused to credit any testimony by which it was impugned.[894] There is reason to believe that his conclusion is erroneous, and that different diseases can so accompany each other, as to be united in the same individual, at the same time, and in the same part.[895] Whether or not this be the case, it is equally interesting to notice the process of thought which led Hunter to bestow infinitely more pains in arguing from the general theory, than in arguing to it. Indeed, he can hardly be said to have argued to it at all, since he obtained it by a rough and hasty generalization from what seemed to be the obvious properties of inorganic matter. Having thus obtained it, he applied it to the pathological phenomena of the organic world, and especially of the animal world. That he should have adopted this course, is a curious proof of the energy of his deductive habits, and of the force of mind which enabled him so to set at naught the traditions of his English contemporaries, as to follow a method which, in the opinion of every one who surrounded him, was not only full of danger, but could never lead to truth.

Other parts of his pathology abound with similar instances, which show how anxious he was to assume principles on which he could build arguments. Of this kind were his ideas respecting sympathy, as connected with action. He suggested, that the simplest forms of sympathy would probably be found in the vegetable world, because there, the general arrangements are less intricate than in the animal world.[896] On this supposition, he constructed a series of curious and refined speculations, of which, however, I must confine myself to giving a very short summary. As animals sympathize more than vegetables, this helps us to understand why it is that their movements are more numerous. For, sympathy, being a susceptibility to impression, is also a principle of action.[897] Like other principles of action, it may be either natural or diseased.[898] But, whichever it be, it can, in plants, have only one mode of development, because, in them, it can only be influenced by stimulus; while in animals, which have sensation, it has necessarily three modes, one from stimulus, one from sensation, and a third compounded of the other two.[899] These are the largest divisions of sympathy, if we consider the organic world as a whole. In single cases, however, sympathy admits of still further subdivision. We may reason from it, in reference to the age of the individual;[900] we may also reason from it in reference to temperament, since, in point of fact, temperament is nothing but susceptibility to action.[901] And when sympathy is in action, we may, by analyzing our idea of it, reduce it to five different heads, and may classify it as continued, or contiguous, or remote, or similar, or dissimilar.[902] All these supplied Hunter with principles from which, by reasoning deductively, he attempted to explain the facts of disease; for, according to him, disease merely consists in a want of combination of actions.[903] By this process of thought, he was induced to neglect those predisposing causes, to which inductive pathologists pay great attention, and with which the works of his English contemporaries were much occupied. Such causes could only be generalized from observation, and Hunter made no account of them. Indeed, he even denies their real existence, and asserts that a predisposing cause is simply an increased susceptibility to form disposition to action.[904]

By reasoning from the twofold ideas of action and of sympathy, Hunter constructed the deductive or synthetic part of his pathology. This he did as a Scotchman, and to this, had he always lived in Scotland, he would probably have confined himself. But being for forty years surrounded by Englishmen, and having his mind impregnated by English habits, he contracted something of their mode of thought. We, accordingly, find that a considerable portion of his pathology is as inductive as the most eager disciple of Bacon could desire; forming, in this respect, a striking contrast to the purely synthetic method of Cullen, the other great pathologist of Scotland. In the attempt, however, which Hunter made to mix these two methods, he perplexed both himself and his readers. Hence that obscurity, which even his warmest admirers have noticed, though they have not perceived its cause. Vast as his powers were, he was unable to effect a complete union between induction and deduction. That this should have happened, will not surprise any one, who considers how some of the greatest thinkers have failed in this, the most difficult of all enterprises. Among the ancients, Plato failed in induction, and all his followers failed with him; since none of them have placed sufficient confidence in facts, and in the process of reasoning from particulars to generals. Among the moderns, Bacon was deficient in deduction, and every Baconian has been similarly deficient; it being the essential vice of that school to despise reasoning from general propositions, and to underrate the value of the syllogism. It may, indeed, be doubted if the history of the world supplies more than two instances of physical philosophers being as great in one form of investigation as in the other. They are Aristotle and Newton, who wielded each method with equal ease, combining the skill and boldness of deduction with the caution and perseverance of induction, masters alike of synthesis and of analysis, as capable of proceeding from generals to particulars, as from particulars to generals, sometimes making ideas precede facts, and sometimes making facts precede ideas, but never faltering, never doubting which course to take, and never allowing either scheme unduly to encroach on its opposite. That Hunter should be unable to perform this, merely proves that he was inferior to these two men, whose almost incredible achievements entitle them to be termed the prodigies of the human race. But what he did was wonderful, and, in his own department, has never been rivalled. Of the character and extent of his inquiries, I have given a sketch, which, notwithstanding its imperfections, may serve to illustrate the antagonism of the Scotch and English intellects, by showing how the methods peculiar to each nation struggled for mastery in that great mind, which was exposed to the action of both. Which method predominated in Hunter, it would be hard to say. But it is certain, that his understanding was troubled by their conflict. It is also certain, that, owing to his love of deduction, or of reasoning from general ideas, he exercised much less sway over his English contemporaries, than he would have done if he had exclusively followed their favourite method of reasoning from particular facts. Hence, the disproportion between his influence and his merits. As to his merits, it is now admitted that, in addition to his physiological discoveries, and the great pathological views which he propounded, we may trace to him nearly all the surgical improvements which were introduced within about forty years after his death.[905] He was the first who explained, and, indeed, the first who recognized, the disease of inflammation of the veins, which is of frequent occurrence, and, under the name of phlebitis, has latterly been much studied, but which, before his time, had been ascribed to the most erroneous causes.[906] On general inflammation, he threw so much light, that the doctrines which he advocated, and which were then ridiculed as whimsical novelties, are now taught in the schools, and have become part of the common traditions of the medical profession.[907] He, moreover, introduced what is probably the most capital improvement in surgery ever effected by a single man; namely, the practice in aneurism of tying the artery at a distance from the seat of disease. This one suggestion has saved thousands of lives; and both the suggestion, and the first successful execution of it, are entirely owing to John Hunter, who, if he had done nothing else, would, on this account alone, have a right to be classed among the principal benefactors of mankind.[908]

But, so far as his own immediate reputation was concerned, all was in vain. He was in the midst of a people who had no sympathy with that mode of thought which was most natural to him. They cared nothing for ideas, except with a few to direct and tangible results; he valued ideas for themselves, and for the sake of their truth, independently of all other considerations. His English contemporaries, prudent, sagacious, but short-sighted, seeing few things at a time, but seeing those things with admirable clearness, were unable to appreciate his comprehensive speculations. Hence, in their opinion, he was little else than an innovator and an enthusiast.[909] Hence, too, even the practical improvements which he introduced were coldly received, because they proceeded from so suspicious a source. The great Scotchman, thrown among a nation whose habits of mind were uncongenial to his own, stood, says one of the most celebrated of his disciples, in a position of solitary and comfortless superiority.[910] Indeed, so little was he regarded by that very profession of which he was the chiefest ornament, that, during the many years in which he delivered lectures in London on anatomy and on surgery, his audience never amounted to twenty persons.[911]

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I have now completed my examination of the Scotch intellect as it unfolded itself in the seventeenth and eighteenth centuries. The difference between those two periods must strike every reader. In the seventeenth century, the ablest Scotchmen wasted their energies on theological subjects, respecting which we have no trustworthy information, and no means of obtaining any. On these topics, different persons and different nations, equally honest, equally enlightened, and equally competent, have entertained, and still entertain, the most different opinions, which they advocate with the greatest confidence, and support by arguments, perfectly satisfactory to themselves, but contemptuously rejected by their opponents. Each side deeming itself in possession of the truth, the impartial inquirer, that is, he who really loves truth, and knows how difficult it is to obtain it, seeks for some means by which he may fairly adjudicate between these conflicting pretensions, and determine which is right and which is wrong. The further he searches, the more he becomes convinced that no such means are to be found, and that these questions, if they do not transcend the limits of the human understanding, do, certainly, transcend its present resources, and have no chance of being answered, while other and much simpler problems are still unsolved. It would be strange, indeed, if we, ignorant of so many lower and subordinate matters, should be able to reach and penetrate these remote and complicated mysteries. It would be strange if we, who, notwithstanding the advances we have made, are still in the infancy of our career, and who, like infants, can only walk with unsteady gait, and are scarce able to move without stumbling, even on plain and level ground, should, nathless, succeed in scaling those dizzy heights, which, overhanging our path, lure us on where we are sure to fall. Unfortunately, however, men are, in every age, so little conscious of their deficiencies, that they not only attempt this impossible task, but believe they have achieved it. Of those who are a prey to this delusion, there are always a certain number, who, seated on their imaginary eminence, are so inflated by the fancied superiority, as to undertake to instruct, to warn, and to rebuke the rest of mankind. Giving themselves out as spiritual advisers, and professing to teach what they have not yet learned, they exhibit in their own persons that most consistent of all combinations, a combination of great ignorance with great arrogance. From this, other evils inevitably follow. The ignorance produces superstition; the arrogance produces tyranny. Hence it is, that, in a country like Scotland, where the pressure of long-continued and adverse circumstances has consolidated the power of these pretenders to wisdom, such sad results become conspicuous in every direction. Not only the national character, but also the national literature, feel their influence, and are coloured by them. It was, therefore, natural that, in Scotland, in the seventeenth century, when the authority of the clergy was most uncontrolled, the consequences of that authority should be most apparent. It was natural that a literature should be created such as that of which I have given some account; a literature which encouraged superstition, intolerance, and bigotry; a literature full of dark misgivings, and of still darker threats; a literature which taught men that it was wrong to enjoy the present, and that it was right to tremble at the future; a literature, in a word, which, spreading gloom on every side, soured the temper, corrupted the affections, numbed the intellect, and brought into complete discredit those bold and original inquiries, without which there can be no advance in human knowledge, and consequently no increase of human happiness.

To this, the literature of the eighteenth century offered a striking and most exhilarating contrast. It seemed as if, in a moment, all was changed. The Baillies, the Binnings, the Dicksons, the Durhams, the Flemings, the Frasers, the Gillespies, the Guthries, the Halyburtons, the Hendersons, the Rutherfords, and the rest of that monkish rabble, were succeeded by eminent and enterprising thinkers, whose genius lighted up every department of knowledge, and whose minds, fresh and vigorous as the morning, opened for themselves a new career, and secured for their country a high place in the annals of European intellect. Something of what they effected, I have endeavoured to narrate; much, however, has been left untold. But I have brought forward sufficient evidence to convince even the most sceptical reader of the splendour of their achievements, and of the difference between the noble literature which they produced, and those wretched compositions which disfigured the preceding century.

Still, great as the difference was, the two literatures had, as I have shown, one important point in common. Both were essentially deductive; and the proof of this I have given at considerable length, because, though it has, so far as I am aware, escaped the attention of all previous inquirers, its consequences were of the utmost moment to the fortunes of Scotland, and are, moreover, full of interest to those who, in their investigations of human affairs, desire to penetrate below the mere surface and symptoms of things.

If we take a general view of those countries where science has been cultivated, we shall find that, wherever the deductive method of inquiry has predominated, knowledge, though often increased and accumulated, has never been widely diffused. On the other hand, we shall find that, when the inductive method has predominated, the diffusion of knowledge has always been considerable, or, at all events, has been beyond comparison greater than when deduction was prevalent. This holds good, not only of different countries, but also of different periods in the same country. It even holds good of different individuals in the same period, and in the same country. If, in any civilized nation, two men, equally gifted, were to propound some new and startling conclusion, and one of these men were to defend his conclusion by reasoning from ideas or general principles, while the other man were to defend his by reasoning from particular and visible facts, there can be no doubt that, supposing all other things the same, the latter man would gain most adherents. His conclusion would be more easily diffused, simply because a direct appeal, in the first instance, to palpable facts, strikes the vulgar with immediate effect; while an appeal to principles is beyond their ken, and as they do not sympathize with it, they are apt to ridicule it. Facts seem to come home to every one, and are undeniable. Principles are not so obvious, and, being often disputed, they have, to those who do not grasp them, an unreal and illusory appearance, which weakens their influence. Hence it is that inductive science, which always gives the first place to facts, is essentially popular, and has on its side those innumerable persons, who will not listen to the more refined and subtle teachings of deductive science. Hence, too, we find historically that the establishment of the modern inductive philosophy, with its varied and attractive experiments, its material appliances, and its constant appeal to the senses, has been intimately connected with the awakening of the public mind, and coincides with that spirit of inquiry, and with that love of liberty, which have been constantly advancing since the sixteenth century. We may assuredly say, that scepticism and democracy are the two leading features of this great scientific movement. The seventeenth century, which ushered in the Baconian philosophy, was remarkable for its insubordinate spirit, especially in the country where that philosophy originated, and where it most flourished. In the next age, it was transplanted into France, and there, too, it worked upon the popular mind, and, was, as I have already pointed out, one of the principal causes of the French Revolution.

If we look still closer into this interesting question, we shall find further corroboration of the view, that the inferences of an inductive philosophy are more likely to be diffused than those of a deductive one. Inductive science rests immediately upon experience, or, at all events, upon experiment, which is merely experience artificially modified. Now, an immense majority of mankind, even in the most advanced countries, are, by the constitution of their minds, incapable of seizing general principles and applying them to daily affairs, without doing serious mischief, either to themselves, or to others. Such an application requires not only great dexterity, but also a knowledge of those disturbing causes which affect the operation of all general theorems. The task, being so difficult to perform, is rarely attempted; and average men, possessed of a tolerably sound judgment, do, with good reason, rely mainly on experience, which is to them a safer and more useful guide than any principle, however accurate and scientific it might be. This begets in their minds a prejudice on behalf of experimental inquiries, and a corresponding dislike of the opposite and more speculative method. And it can, I think, hardly be doubted, that one of the causes of the triumph of the Baconian philosophy, is the growth of the industrious classes, whose business-like and methodical habits are eminently favourable to empirical observations of the uniformities of sequence, since, indeed, on the accuracy of such observations the success of all practical affairs depends. Certainly, we find that the overthrow of the purely deductive scholasticism of the Middle Ages has been everywhere accompanied by the spread of trade; and whoever will carefully study the history of Europe, will discern many traces of a connexion between the two movements, both of which are marked by an increasing respect for material and empirical interests, and a disregard of ideal and speculative pursuits.

The relation between all this and the popular tendency of induction is obvious. For one person who can think, there are at least a hundred persons who can observe. An accurate observer is, no doubt, rare; but an accurate thinker is far rarer. Of this the proofs are too abundant to be disputed. Indeed, no one can mix with his fellow-creatures, without seeing how much more natural it is for them to notice than to reflect; and how extremely unusual it is to meet with any one whose conversation, or whose writings, bear marks of patient and original thought. And, inasmuch as thinkers are more prone to accumulate ideas, while observers are more prone to accumulate facts, the overwhelming predominance of the observing class is a decisive reason why induction, which begins with facts, is always more popular than deduction, which begins with ideas. It is often said, and probably with truth, that all deduction is preceded by induction; so that, in every syllogism, the major premiss, however obvious and necessary it may appear, is merely a generalization of facts, or record of what the senses had already observed. But this opinion, whether true or false, does not affect what I have just stated, because it concerns the origin of our knowledge, and not its subsequent treatment; that is to say, it is a metaphysical opinion, rather than a logical one. For, even supposing that all deduction rests ultimately on induction, it is, nevertheless, certain that there are innumerable cases in which the induction takes place at so early a period of life that we are unconscious of it, and can by no effort recall the process. The axioms of geometry afford a good specimen of this. No one can tell when or how he first believed that the whole is greater than its part, or that things which are equal to the same thing are equal to one another. All these preliminary steps are concealed from us, and the strength and dexterity of deduction are displayed in the subsequent steps by which the major premiss is adjusted, and, as it were, fitted to the minor. This often requires great subtlety of thought, and, in every instance, the external world is put aside, and lost sight of. The process, being ideal, has no concern, either with observations or experiments. The suggestions of the senses are shut out, while the mind passes through a long train of successive syllogisms, in which each conclusion is turned into the premiss of a new argument, until, at length, an inference is deductively obtained, which, to those who merely hear it enunciated, seems to have no connexion with the first premisses, though, in reality, it is the necessary consequence of them.

A method, so recondite, and so hidden from the public gaze, can never command the public sympathy. Unless, therefore, the human mind should undergo some remarkable change in its nature as well as in its resources, the sensuous process of working upwards from particular facts to general principles, will always be more attractive than the ideal process of working downwards from principles to facts. In both cases, there is, no doubt, a line of argument essentially ideal; just as, in both cases, there is an assemblage of facts essentially sensuous. No method is pure, or stands entirely by itself. But, inasmuch as, in induction, the facts are more prominent than the ideas, while, in deduction, the ideas are more prominent than the facts, it is evident that conclusions arrived at by the former plan will, as a general rule, obtain a wider assent than conclusions arrived at by the latter plan. Obtaining a wider assent, they will produce more decisive results, and will be more likely to shape the national character and influence the course of national affairs.

The only exception to this, is theology. There, the inductive method, as I have already observed, is inapplicable, and nothing remains but deduction, which is quite sufficient for the purposes of the theologian. For, he has a peculiar resource which supplies him with general principles, from which he can argue; and the possession of this resource forms the fundamental difference between him and the man of science. Science is the result of inquiry; theology is the result of faith. In the one, the spirit of doubt; in the other, the spirit of belief. In science, originality is the parent of discovery, and is, therefore, a merit; in theology, it is the parent of heresy, and is, therefore, a crime. Every system of religion the world has yet seen, recognizes faith as an indispensable duty; but to every system of science it is a hindrance, instead of a duty, inasmuch as it discourages those inquisitive and innovating habits on which all intellectual progress depends. The theologian, thus turning credulity into an honour, and valuing men in proportion as they are simple-minded and easy of belief, has little need to trouble himself with facts, which, indeed, he sets at open defiance, in his eagerness to narrate portentous, and often miraculous, events. To the inductive philosopher such a license is forbidden. He is obliged to ground his inferences on facts which no one disputes, or which, at all events, any one can either verify for himself, or see verified by others. And if he does not adopt this course, his inferences, be they ever so true, will have the greatest difficulty in working themselves into the popular mind, because they will savour of a subtlety and refinement of thought, which, more than any thing else, predisposes common understandings to reject the conclusions at which philosophers arrive.

From the facts and arguments contained in this and the preceding chapter, the reader will, I trust, be able to see why it was that the Scotch intellect, during the seventeenth and eighteenth centuries, was preËminently deductive; and also why it was that, in the eighteenth century, the Scotch literature, notwithstanding its brilliancy, its power, and the splendid discoveries of which it was the vehicle, produced little or no effect on the nation at large. That literature, by its bold and innovating character, seemed peculiarly fitted to disturb ancient prejudices, and to rouse up a spirit of inquiry. But its method, both of investigation and of proof, was too refined to suit ordinary understandings. Therefore, upon ordinary understandings it was inoperative. In Scotland, as in ancient Greece, and in modern Germany, the intellectual classes, being essentially deductive, have been unable to influence the main body of the people. They have considered things at too great an altitude, and at too great a remove. In Greece, Aristotle alone had a true idea of what induction really was. But even he knew nothing of crucial instances and the theory of averages, the two capital resources of that inductive philosophy which we now possess. Neither did he, nor any of the great German philosophers, nor any of the great Scotch philosophers, attach sufficient importance to the slow and cautious method of gradually rising from each generalization to the one immediately above it, without omitting any intermediate generalizations. On this method, Bacon, indeed, insists too strongly, since many most important discoveries have been made independently of it, or, I should rather say, in contradiction to it. But it is a wonderful weapon, and none except men of real genius can dispense with its use. And when they do dispense with it, they cut themselves off from the general sympathies of their age and country. For, these small and proximate generalizations, which they neglect, are precisely those parts of philosophy which, being least removed from the region of visible facts, are best understood by the people, and, therefore, form the only common ground between thinkers and practitioners. They are a sort of middle term, which, being comprehended by both classes, is accessible to either. In all deductive reasoning, this intermediate, and, if I may so say, neutral, territory disappears, and the two classes have no meeting-place. Hence it is, that the Scotch philosophy, like the German philosophy, and like the Greek philosophy, has had no national influence. But in England, since the seventeenth century, and in France, since the eighteenth century, the prevailing philosophy has been inductive, and has, therefore, not only affected the intellectual classes, but also moved the public mind. The German philosophers are far superior, both in depth and in comprehensiveness, to the philosophers either of France or of England. Their profound researches have, however, done so little for their country, that the German people are every way inferior to the French and English people. So, too, in the philosophy of ancient Greece, we find a vast body of massive and original thought, and, what is infinitely better, we find a boldness of inquiry and a passionate love of truth, such as no modern nation has surpassed, and few modern nations have equalled. But the method of that philosophy was an insuperable barrier to its propagation. The people were untouched, and went grovelling on in their old folly, a prey to superstitions, most of which the great thinkers despised, and often attacked, but could by no means root out. Bad, however, as those superstitions were, we may confidently say that they were less noxious, that is, less detrimental to the happiness of man, than the repulsive and horrible notions advocated by the Scotch clergy, and sanctioned by the Scotch people. And on those notions the Scotch philosophy could make no impression. In Scotland, during the eighteenth century, superstition and science, the most irreconcilable of all enemies, flourished side by side, unable to weaken each other, and unable, indeed, to come into collision with each other. There was co-existence without contact. The two forces kept apart, and the result was, that, while the Scotch thinkers were creating a noble and most enlightened literature, the Scotch people, refusing to listen to those great masters of wisdom which their country possessed, remained in darkness, leaving the blind to follow the blind, and no one there to help them.

It is, indeed, curious to observe how little effect was produced by the many great works written by Scotchmen in the eighteenth century. If we except the Wealth of Nations, I can hardly call to mind one which has perceptibly influenced public opinion. The reason of this exception may be easily explained. The Wealth of Nations restricted the action of government within narrower limits than had ever been assigned to it by any other book of great merit. No previous political writer of admitted genius, had left so much to the people, and had demanded for them so much liberty in managing their own affairs, as Adam Smith did. The Wealth of Nations, being thus eminently a democratic book, was sure to find favour in Scotland, which was eminently a democratic country. Directly men heard its conclusions, they were prejudiced in favour of its arguments. So, too, in England, that love of liberty, which for many centuries has been our leading characteristic, and which does us more real honour than all our conquests, all our literature, and all our philosophy put together, invariably causes a popular bias on behalf of any claim to freedom. We, therefore, notwithstanding the activity of interested parties, were predisposed to the side of free trade, as one of the means of letting each man do what he liked with his own. But to imagine that ordinary minds are capable of mastering such a work as the Wealth of Nations, and of following without confusion its long and intricate arguments, is simply absurd. It has been read by tens of thousands of persons, who accept its conclusions because they like them; which is merely saying, because the movement of the age tends that way. The other great work of Adam Smith, namely, the Theory of Moral Sentiments, has had no influence except on a very small class of metaphysicians, although its style is, as some think, superior to the Wealth of Nations, and it is certainly easier to understand. It is, moreover, much shorter, which, to most readers, is no small recommendation; and it deals with subjects of great interest, which come home to the feelings of all. But the age, not caring for its conclusions, neglected its arguments. On the other hand, the Wealth of Nations harmonized with the general tendency, and its success was supreme. It quickly moved, not only philosophers, but even statesmen and politicians, who eventually put into force its leading recommendations, though, as their laws and their speeches abundantly prove, they have never succeeded in mastering those great principles which underlie it, and of which the freedom of trade is but a minor accessory.

Putting aside the Wealth of Nations, we shall find that the Scotch literature of the eighteenth century did scarcely any thing for Scotland, considered as a whole. How it has failed in its great aim of weakening superstition, is but too apparent to whoever has travelled in that country, and observed the habits and turn of mind still predominant. Many able and enlightened men who lived there, are so cowed by the general spirit, that, for their own comfort, and for the peace of their families, they make no resistance, but tacitly comply with what they heartily despise. That they err in doing so, I, at least, firmly believe; though I know that many honest, and in every respect competent, judges are of opinion, that no man is bound to be a martyr, or to jeopardize his personal interests, unless he clearly sees his way to some immediate public good. To me, however, it appears that this is a narrow view, and that the first duty of every one is to set his face in direct opposition to what he believes to be false, and, having done that, leave the results of his conduct to take care of themselves. Still, the temptation to a contrary course is always very strong, and, in a country like Scotland, is by many deemed irresistible. In no other Protestant nation, and, indeed, in no Catholic nation except Spain, will a man who is known to hold unorthodox opinions, find his life equally uncomfortable. In a few of the large towns, he may possibly escape animadversion, if his sentiments are not too bold, and are not too openly expressed. If he is timid and taciturn, his heresy may, perchance, be overlooked. But even in large towns, impunity is the exception, and not the rule. Even in the capital of Scotland, in that centre of intelligence which once boasted of being the Modern Athens, a whisper will quickly circulate that such an one is to be avoided, for that he is a free-thinker; as if free-thinking were a crime, or as if it were not better to be a free-thinker than a slavish thinker. In other parts, that is, in Scotland generally, the state of things is far worse. I speak, not on vague rumour, but from what I know as existing at the present time, and for the accuracy of which I vouch and hold myself responsible. I challenge any one to contradict my assertion, when I say that, at this moment, nearly all over Scotland, the finger of scorn is pointed at every man, who, in the exercise of his sacred and inalienable right of free judgment, refuses to acquiesce in those religious notions, and to practise those religious customs, which time, indeed, has consecrated, but many of which are repulsive to the eye of reason, though to all of them, however irrational they maybe, the people adhere with sullen and inflexible obstinacy. Knowing that these words will be widely read and circulated in Scotland, and averse as I naturally am to bring on myself the hostility of a nation, for whose many sterling and valuable qualities I entertain sincere respect, I do, nevertheless, deliberately affirm, that in no civilized country is toleration so little understood, and that in none is the spirit of bigotry and of persecution so extensively diffused. Nor can any one wonder that such should be the case, who observes what is going on there. The churches are as crowded as they were in the Middle Ages, and are filled with devout and ignorant worshippers, who flock together to listen to opinions of which the Middle Ages alone were worthy. Those opinions they treasure up, and, when they return to their homes, or enter into the daily business of life, they put them in force. And the result is, that there runs through the entire country a sour and fanatical spirit, an aversion to innocent gaiety, a disposition to limit the enjoyments of others, and a love of inquiring into the opinions of others, and of interfering with them, such as is hardly anywhere else to be found; while, in the midst of all this, there flourishes a national creed, gloomy and austere to the last degree, a creed which is full of forebodings and threats and horrors of every sort, and which rejoices in proclaiming to mankind how wretched and miserable they are, how small a portion of them can be saved, and what an overwhelming majority is necessarily reserved for excruciating, unspeakable, and eternal agony.

Before bringing this volume to a close, it may be fitting that I should narrate an event, which, notwithstanding its recent occurrence, and the great attention it excited at the time, has, amid the pressure of weightier matters, fallen into comparative oblivion, although it is full of interest to those who study the various forms of national character, while it, moreover, supplies an admirable illustration of the essential antagonism which still exists between the Scotch and English minds; an antagonism extremely remarkable, when found among nations, both of whom, besides being contiguous, and constantly mixing together, speak the same language, read the same books, belong to the same empire, and possess the same interests, and yet are, in many important respects, as different as if there had never been any means of their influencing each other, and as if they had never had any thing in common.

In the year 1853, the cholera, after having committed serious ravages in many parts of Europe, visited Scotland. There, it was sure to find numerous victims among a badly fed, badly housed, and not over-cleanly people. For, if there is one thing better established than another respecting this disease, it is that it invariably attacks, with the greatest effect, those classes who, from poverty or from sloth, are imperfectly nourished, neglect their persons, and live in dirty, ill-drained, or ill-ventilated dwellings. In Scotland, such classes are very numerous. In Scotland, therefore, the cholera must needs be very fatal. In this, there was nothing mysterious. On the contrary, the mystery would have been if an epidemic, like the Asiatic cholera, had spared a country like Scotland, where all the materials were collected on which pestilence feeds, and where filth, penury, and disorder, abound on every side.

Under these circumstances, it must have been evident, not merely to men of science, but to all men of plain, sound understanding, who would apply their minds to the matter without prejudice, that the Scotch had only one way of successfully grappling with their terrible enemy. It behoved them to feed their poor, to cleanse their cesspools, and to ventilate their houses. If they had done this, and done it quickly, thousands of lives would have been spared. But they neglected it, and the country was thrown into mourning. Nay, they not only neglected it, but, moved by the dire superstition which sits like an incubus upon them, they adopted a course which, if it had been carried into full operation, would have aggravated the calamity to a frightful extent. It is well known that, whenever an epidemic is raging, physical exhaustion and mental depression make the human frame more liable to it, and are, therefore, especially to be guarded against. But, though this is a matter of common notoriety, the Scotch clergy, backed, sad to say, by the general voice of the Scotch people, wished the public authorities to take a step which was certain to cause physical exhaustion, and to encourage mental depression. In the name of religion, whose offices they thus abused and perverted to the detriment of man, instead of employing them for his benefit, they insisted on the propriety of ordering a national fast, which, in so superstitious a country, was sure to be rigidly kept, and, being rigidly kept, was equally sure to enfeeble thousands of delicate persons, and, before twenty-four hours were passed, prepare them to receive that deadly poison which was already lurking around them, and which, hitherto, they had just strength enough to resist. The public fast was also to be accompanied by a public humiliation, in order that nothing might be wanting to appal the mind and fill it with terror. On the same occasion, the preachers were to thunder from their pulpits and proclaim aloud the sins of the land; while the poor benighted people, panic-struck, were to sit in awe, were to remain the whole day without proper nourishment, and retire to their beds, weeping and starved. Then it was hoped that the Deity would be propitiated, and the plague be stayed. As soon as the entire nation had taken the course, which, of all others, was most certain to increase the mortality, it was believed that man having done his worst, the Almighty would interpose, would violate the laws of nature, and, by working a miracle, would preserve his creatures from what, without a miracle, would be the inevitable consequence of their own deliberate act.

This was the scheme projected by the Scotch clergy, and they were determined to put it into execution. To give greater effect to it, they called upon England to help them, and, in the autumn of 1853, the Presbytery of Edinburgh, thinking that from their position they were bound to take the lead, caused their Moderator to address a letter, ostensibly to the English Minister, but in reality to the English nation. In this choice production, a copy of which is now lying before me, the Home Secretary is assured that the members of the Presbytery had delayed appointing a day for fasting and humiliation on their own ecclesiastical authority, because they thought it likely that one would be appointed by the royal authority. But as this had not been done, the Presbytery respectfully requested to be informed if it was intended to be done. They apologized for the liberty they were taking; they had no desire unduly to intrude themselves; neither did they wish the Home Secretary to answer their question unless he felt himself justified in doing so. Still, if he were able to answer it, they would be glad. For, there was no doubt that Asiatic cholera was in the country; and such being the case, the Presbytery of Edinburgh were interested in knowing if the appointment by the Queen of a national fast was in contemplation.[912]

This letter, which, through the medium of the press, was sure to become well known and to be widely read, was evidently intended to act on public opinion in England. It was, in fact, a covert reproach on the English Government for having neglected its spiritual duties, and for not having perceived that fasting was the most effectual way of stopping an epidemic. In Scotland, generally, it received great praise, and was regarded as a dignified rebuke addressed to the irreligious habits of the English people, who, seeing the cholera at their doors, merely occupied themselves with sanatory measures, and carnal devices to improve the public health, showing thereby that they trusted too much to the arms of the flesh. In England, on the other hand, this manifesto of the Scotch Church was met with almost universal ridicule, and, indeed, found no favourers except among the most ignorant and credulous part of the nation. The minister to whom it was addressed, was Lord Palmerston, a man of vast experience, and perhaps better acquainted with public opinion than any politician of his time. He, being well aware of the difference between Scotland and England, knew that what was suitable for one country was not suitable for the other, and that notions which the Scotch deemed religious, the English deemed fanatical. On a former occasion, the imperial government, yielding to the clamour which a few active and interested men succeeded in raising, had been foolish enough to set themselves in this matter in opposition to the temper of the age, and to enjoin public observances which, happily, were not strictly obeyed, but which, in so far as they were obeyed, heightened the general terror by reinforcing natural fears with supernatural ones, and thus, depressing the nervous system, increased the chance of mortality from the pestilence. To have the plague in our country is bad enough, since, do what we may, many victims will be struck down by it. But a fearful responsibility is entailed upon those who, at such a period, instead of exerting themselves to check its ravages, either by precautionary measures, or by soothing and re-assuring the people, do every thing in their power to aggravate the calamity, by encouraging that superstitious dread which weakens the popular energy at the very moment when energy is most requisite, and troubles the coolness, the self-reliance, and self-possession, without which no crisis of national danger can ever be averted.

This time, however, there was no risk of the government committing so serious a blunder. Lord Palmerston, who knew that the sound sense of the English people would support him in what he was doing, directed a letter to be sent to the Presbytery of Edinburgh, which, unless I am greatly mistaken, will, in future ages, be quoted as an interesting document for illustrating the history of the progress of public opinion. A century ago, any statesman who had written such a letter, would have been driven from office by a storm of general indignation. Two centuries ago, the consequences to him would have been still more disastrous, and would, indeed, have ruined him socially, as well as politically. For, in it, he sets at defiance those superstitious fancies respecting the origin of disease, which were once universally cherished as an essential part of every religious creed. Traditions, the memory of which is preserved in the theological literature of all Pagan countries, of all Catholic countries, and of all Protestant countries, are quietly put aside, as if they were matters of no moment, and as if it were not worth while to discuss them. The Scotch clergy, occupying the old ground on which the members of their profession had always been accustomed to stand, took for granted that the cholera was the result of the divine anger, and was intended to chastise our sins. In the reply which they now received from the English Government, a doctrine was enunciated, which to Englishmen seems right enough, but which to Scotchmen sounded very profane. The Presbytery were informed, that the affairs of this world are regulated by natural laws, on the observance or neglect of which the weal or woe of mankind depends.[913] One of those laws connects disease with the exhalations of bodies; and it is by virtue of this law that contagion spreads, either in crowded cities, or in places where vegetable decomposition is going on. Man, by exerting himself, can disperse or neutralize these noxious influences. The appearance of the cholera proves that he has not exerted himself. The towns have not been purified; hence the root of the evil. The Home Secretary, therefore, advised the Presbytery of Edinburgh, that it was better to cleanse than to fast. He thought that the plague being upon them, activity was preferable to humiliation. It was now autumn, and before the hot weather would return, a considerable period must elapse. That period should be employed in destroying the causes of disease, by improving the abodes of the poor. If this were done, all would go well. Otherwise, pestilence would be sure to revisit them, ‘in spite’—I quote the words of the English minister—‘in spite of all the prayers and fastings of a united, but inactive nation.’[914]

This correspondence between the Scotch clergy and the English statesman, is not to be regarded as a mere passing episode of light or temporary interest. On the contrary, it represents that terrible struggle between theology and science, which, having begun in the persecution of science, and in the martyrdom of scientific men, has, in these later days, taken a happier turn, and is now manifestly destroying that old theological spirit, which has brought so much misery and ruin upon the world. The ancient superstition, which was once universal, but is now slowly though surely dying away, represented the Deity as being constantly moved to anger, delighting in seeing His creatures abase and mortify themselves, taking pleasure in their sacrifices and their austerities, and, notwithstanding all they could do, constantly inflicting on them the most grievous punishments, among which the different forms of pestilence were conspicuous. It is by science, and by science alone, that these horrible delusions are being dissipated. Events, which formerly were deemed supernatural visitations, are now shown to depend upon natural causes, and to be amenable to natural remedies. Man can predict them, and man can deal with them. Being the inevitable result of their own antecedents, no room is left for the notion of their being special inflictions. This great change in our opinions is fatal to theology, but is serviceable to religion. For, by it, science, instead of being the enemy of religion, becomes its ally. Religion is to each individual according to the inward light with which he is endowed. In different characters, therefore, it assumes different forms, and can never be reduced to one common and arbitrary rule. Theology, on the other hand, claiming authority over all minds, and refusing to recognize their essential divergence, seeks to compel them to a single creed, and sets up one standard of absolute truth, by which it tests every one's opinions; presumptuously condemning those who disagree with that standard. Such arrogant pretensions need means of support. Those means are threats, which, in ignorant times, are universally believed, and which, by causing fear, produce submission. Hence it is, that the books of every theological system narrate acts of the grossest cruelty, which, without the least hesitation, are ascribed to the direct interposition of God. Humane and gentle natures revolt at such cruelties, even while they try to believe them. It is the business of science to purify theology, by showing that there has been no cruelty, because there has been no interposition. Science ascribes to natural causes, what theology ascribes to supernatural ones. According to this view the calamities with which the world is afflicted, are the result of the ignorance of man, and not of the interference of God. We must not, therefore, ascribe to Him what is due to our own folly, or to our own vice. We must not calumniate an all-wise and all-merciful Being, by imputing to Him those little passions which move ourselves, as if He were capable of rage, of jealousy, and of revenge, and as if He, with outstretched arm, were constantly employed in aggravating the sufferings of mankind, and making the miseries of the human race more poignant than they would otherwise be.

That this remarkable improvement in religious ideas is due to the progress of physical science, is apparent, not only from general arguments which would lead us to anticipate that such must be the case, but also from the historical fact, that the gradual destruction of the old theology is everywhere preceded by the growth and diffusion of physical truths. The more we know of the laws of nature, the more clearly do we understand that every thing which happens in the material world, pestilence, earthquake, famine, or whatever it may be, is the necessary result of something which had previously happened. Cause produces effect, and the effect becomes, in its turn, a cause of other effects. In that operation, we see no gap, and we admit of no pause. To us, the chain is unbroken; the constancy of nature is unviolated. Our minds become habituated to contemplate all physical phenomena as presenting an orderly, uniform, and spontaneous march, and running on in one regular and uninterrupted sequence. This is the scientific view. It is also the religious view. Against it, we have the theological view; but that which has already lost its hold over the intellect of men is now losing its hold over their affections, and is so manifestly perishing, that at present no educated person ventures to defend it, without so limiting and guarding his meaning, as to concede to its opponents nearly every point which is really at issue.

While, however, in regard to the material world, the narrow notions formerly entertained, are, in the most enlightened countries, almost extinct, it must be confessed that, in regard to the moral world, the progress of opinion is less rapid. The same men who believe that Nature is undisturbed by miraculous interposition, refuse to believe that man is equally undisturbed. In the one case, they assert the scientific doctrine of regularity; in the other, they assert the theological doctrine of irregularity. The reason of this difference of opinion is, that the movements of nature are less complex than the movements of man. Being less complex, they are more easily studied, and more quickly understood. Hence we find, that while natural science has long been cultivated, historical science hardly yet exists. Our knowledge of the circumstances which determine the course of mankind, is still so imperfect, and has been so badly digested, that it has produced scarcely any effect on popular ideas. Philosophers, indeed, are aware, that here, as elsewhere, there must be a necessary connexion between even the most remote and dissimilar events. They know that every discrepancy is capable of being reconciled, though we, in the present state of knowledge, may be unequal to the task. This is their faith, and nothing can wean them from it. But the great majority of people have a different faith. They believe that what is unexplained is inexplicable, and that what is inexplicable is supernatural. Science has explained an immense number of physical phenomena, and therefore, even to the vulgar, those phenomena no longer seem supernatural, but are ascribed to natural causes. On the other hand, science has not yet explained the phenomena of history; consequently, the theological spirit lays hold of them, and presses them into its own service. In this way there has arisen that famous and ancient theory, which has received the name of the moral government of the world. It is a high-sounding title, and imposes on many, who, if they examined its pretensions, would never be duped by them. For, like that other notion which we have just considered, it is not only unscientific, but it is eminently irreligious. It is, in fact, an impeachment of one of the noblest attributes of the Deity. It is a slur on the Omniscience of God. It assumes that the fate of nations, instead of being the result of preceding and surrounding events, is specially subject to the control and interference of Providence. It assumes that there are great public emergencies, in which such interference is needed. It assumes, that, without the interference, the course of affairs could not run smoothly; that they would be jangled and out of tune; that the play and harmony of the whole would be incomplete. And thus it is, that the very men who, at one moment, proclaim the Divine Omniscience, do, at the next moment, advocate a theory which reduces that Omniscience to nothing, since it imputes to an All-wise Being, that the scheme of human affairs, of which He must, from the beginning, have foreseen every issue and every consequence, is so weakly contrived as to be liable to be frustrated; that it has not turned out as He could have wished; that it has been baffled by His own creatures, and that, to preserve its integrity, its operations must be tampered with, and its disorders redressed. The great Architect of the universe, the Creator and Designer of all existing things, is likened to some clumsy mechanic, who knows his trade so ill, that he has to be called in to alter the working of his own machine, to supply its deficiencies, to fill up its flaws, and to rectify its errors.

It is time that such unworthy notions should come to an end. It is time that what has long been known to philosophers, should also be known to historians, and that the history of mankind should cease to be troubled by what, to those who are imbued with the scientific spirit, must seem little better than arrant trifling. Of two things, choose one. Either deny the Omniscience of the Creator, or else admit it. If you deny it, you deny what, to my mind at least, is a fundamental truth, and, on these matters, there can be no sympathy between us. But if you admit the Omniscience of God, beware of libelling what you profess to defend. For when you assert what is termed the moral government of the world, you slander Omniscience, inasmuch as you declare that the mechanism of the entire universe, including the actions both of Nature and of Man, planned as it is by Infinite Wisdom, is unequal to its duties, unless that same Wisdom does from time to time interfere with it. You assert, in fact, either that Omniscience has been deceived, or that Omnipotence has been defeated. Surely, they who believe, and whose pride and happiness it is to believe, that there is a Power above all and before all, knowing all and creating all, ought not to fall into such a snare as this. They who, dissatisfied with this little world of sense, seek to raise their minds to something which the senses are unable to grasp, can hardly fail, on deeper reflection, to perceive how coarse and material is that theological prejudice, which ascribes to such a Power the vulgar functions of a temporal ruler, arrays him in the garb of an earthly potentate, and represents him as meddling here and meddling there, uttering threats, inflicting punishments, bestowing rewards. These are base and grovelling conceptions, the offspring of ignorance and of darkness. Such gross and sordid notions are but one remove from actual idolatry. They are the draff and offal of a bygone age, and we will not have them obtruded here. Well suited they were to those old and barbarous times, when men, being unable to refine their ideas, were, therefore, unable to purify their creed. Now, however, they jar upon us; they do not assimilate with other parts of our knowledge; they are incongruous; their concord is gone. Every thing is against them. They stand alone; there is nothing left with which they harmonize. The whole scope and tendency of modern thought force upon our minds conceptions of regularity and of law, to which they are diametrically opposed. Even those who cling to them, do so from the influence of tradition, rather than from complete and unswerving belief. That child-like and unhesitating faith, with which the doctrine of interposition was once received, is succeeded by a cold and lifeless assent, very different from the enthusiasm of former times. Soon, too, this will vanish, and men will cease to be terrified by phantoms which their own ignorance has reared. This age, haply, may not witness the emancipation; but, so surely as the human mind advances, so surely will that emancipation come. It may come quicker than any one expects. For, we are stepping on far and fast. The signs of the time are all around, and they who list may read. The handwriting is on the wall; the fiat has gone forth; the ancient empire shall be subverted; the dominion of superstition, already decaying, shall break away, and crumble into dust; and new life being breathed into the confused and chaotic mass, it shall be clearly seen, that, from the beginning, there has been no discrepancy, no incongruity, no disorder, no interruption, no interference; but that all the events which surround us, even to the furthest limits of the material creation, are but different parts of a single scheme, which is permeated by one glorious principle of universal and undeviating regularity.

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