As clear fountains send forth pellucid streams, so do clear truths give accurate sciences. The more definite the facts, the more perfect the science; it is therefore of importance that all facts should be capable of being tested by the standard of physical certainty. Dr. Reid says, that 'the inquirer after truth must take only facts for his guide.' It is then of moment that he takes true and not false guides. A writer in the 'Monthly Repository' observes, that 'the basis of all knowledge is such an extensive induction from particular facts, as leads to general conclusions and fundamental axioms'—and if the facts are erroneous, evidently the conclusions will be also erroneous. He also remarks, that 'in reasoning, all sciences are the same, being founded on an examination of facts—comparison of ideas.' But If the examination is incomplete, or the facts admitted incorrect, the comparison will be alike defective and the reasoning vitiated. If suppositions or conjectures are mixed up with facts, the inductions from them will be suppositions, and the conclusions but conjectures.

There are three words—consciousness, conscience, and conscientiousness—very much alike to the ear but very different in signification. Consciousness, is feeling—conscience, the sense of right and wrong—-conscientiousness, the practice of what is believed to be right. Conscience and conscientiousness are often confounded. We say, lawyers have no conscience, we mean no conscientiousness. They know right from wrong as men, but not professionally. It is with consciousness that the logician has to deal. Consciousness is the primary source of knowledge. Consciousness and the 'Evidences of the Senses' are synonymous terms. Facts referable to consciousness are said to be physically certain. The evidence of the senses is the highest standard of certainty.

The intuitive principles of belief are—

These truths of intuition or consciousness are the foundation of all knowledge. Truths which we know, by way of inference, are occurrences which took place while we were absent—the events of history and the theorems of mathematics. But the truths known by intuition are the original premises from which all others axe inferred. Our assent to the conclusion being grounded upon the truth of the premises, we could never arrive at any knowledge by reasoning, unless something could be known antecedently to all reasoning.

'Whatever is known to us by consciousness, is known beyond possibility of question. What one sees, or feels, whether bodily or mentally, one cannot but be sure that one sees or feels. No science is required for the purpose of establishing such truths; no rules of art can render our knowledge of them more certain than it is in itself. There is no logic for this portion of our know ledge.'*

All discussions pertaining to the nature and limits of intuition or consciousness are referred to the higher or transcendental metaphysics, but all the facts that compose evidence and become the grounds of inference are, according to the view taken here, necessarily subjects of examination.

'Cogito ergo sum—I think, therefore I am, argued Des Cartes. We learn by this that consciousness of the operations of the mind is the strongest evidence of our existence. It cannot be proved so forcibly by any other means; and although Des Cartes' language may appear to involve a logical fallacy, yet the proof of our personal existence which we have from thinking, is the fullest and best we are acquainted with.'**

There is a numerous class of facts from which all men draw conclusions, which facts are not referable to the evidence of the senses. There are the facts of testimony. Testimony is founded on laws almost as fixed and certain as those of nature. All our knowledge, scientific, literary, historical—all except what arises from our experience and consciousness—depends on it. In the administration of justice it is the sole guardian of property and life. If a man of known integrity and veracity state a fact, without any possible motive of self-interest, and evidently subject to no delusion; and if others of like character, who could have no understanding or collusion with him, state the same, men are nearly as certain of it as of any truth in mathematics. I believe in the existence of Rome and the facts of astronomy on this evidence, although I never saw the city or examined the stars through a telescope.

The conclusiveness of testimony is designated moral certainty. The value of testimony depends on three things. 1. On the nature of the subject. Some subjects are capable of more accurate observation than others. 2. On the powers and character of the observer—his ability to understand or note that of which he testifies—and his honesty in common matters. 3. On the number of our informers. Several persons are less likely to be imposed upon than one.

Testimony or moral certainty is inferior to physical certainty. A physical certainty bears uniformly the name of certainty, while a moral certainty is characterised as a probability. Great, very great may be the probability, still it is less in reliableness than a physical certainty. The evidence of Cato or Aristides would be very conclusive—yet somewhat less certain than that which our own senses have proved.

The conclusions from moral certainties are obtained like other conclusions, by induction. The induction from moral facts is like the induction from physical facts, with this difference—that the conclusions from moral facts are probabilities, like the facts on which they are founded. Whatever has physical certainty in its favour is considered demonstrable, and when sufficient probable evidence is adduced in favour of a proposition, it is considered to be fairly proved. Some persons, biased by the strictness of mathematical proof, insist upon the same accuracy in moral investigations. I have elsewhere pointed out the juvenility and infatuation of this error. Insist upon demonstration where the nature of the questions admits it. Less should not, in such case, suffice. Accept probability where probability is the sole evidence attainable. Never ask more than reason can grant. We must admit gradations of validity. What we are conscious of, we know. All we receive on testimony, we believe. Physical certainty is knowledge: moral certainty, belief. Hume remarks, in his 'Essay on Probabilities,' that 'Mr. Locke divides all arguments into demonstrative and probable. In this view, we must say, that it is only probable all men must die, or that the sun will rise to-morrow. But to conform our language more to common us, we ought to divide arguments into demonstrations, proofs, and probabilities. By proofs, meaning such arguments from experience as leave no room for doubt or opposition.'*

Conjecture is probable truth. Some subjects only furnish a sufficient number of facts to make them probable in the lowest degree—not to decide them as positively true. The propositions expressing results pertaining to such subjects are called conjectures.

A conjecture founded on no fact or upon too few to make it likely, is called a vagary.

It will be seen that probability is a thing of degree. A probability may vary in weight from a moral certainty, where it ranks next to a physical certainty, down to a conjecture, and descend lower in likelihood till it is lost in conjecture.

Lord Kames remarks, in his preface to his 'Sketches'—'Most of the subjects handled in the following sheets, admit but of probable reasoning: and, with respect to such reasoning, it is often difficult to say, what degree of conviction they ought to produce. It is easy to form plausible arguments; but to form such as can stand the test of time, is not always easy. I could amuse the reader with numerous examples of conjectural arguments, which, fair at a distant view, vanish like a cloud on a near approach'. Did all authors so judiciously apprise their readers of the probable logical value of their speculations, fewer would be misled than now.

To numerous questions of undoubted interest, which have been agitated in all ages, only a moderate degree of certainty attaches—these are termed speculative. Such subjects may afford but few facts and instances, and the chances of conclusiveness may seem remote—yet ultimate results are not to be despaired of: the new comparison of conjectures and the arrangement of facts daily throws new light on age-contested points. Systems of conduct should not be founded on conjectures in opposition to evident moral utility; but if speculation is kept 'within the sphere of speculation, it may be prosecuted with safety and prospect of success.

There are problems in metaphysics as there are in mathematics, which may be demonstrated to be insolvable. To describe the limit of human power with respect to contested questions will yet result from speculative controversy. The capacities of our understanding will be one day well considered, the extent of our knowledge discovered, and the horizon found which sets bounds between the enlightened and the dark part of things—between what is and what is not comprehensible by us. But this will only be when the untried has been universally attempted in all directions. Bailey, I think, has defined truth as being that which is universally accepted after having been universally examined. Little of this truth is yet extant. When every man shall be a thinker, when the autobiography of intellect shall be more freely furnished than it ever yet has been, unanimity of opinion not yet dreamed of will prevail. Harmony of opinion is the sign of intellectual conquest—the standard-bearer of truth no advocacy is victorious while dissent occupies the field.

What we know to be true, is knowledge; what we have only reason to believe true, is opinion. All human information is made up of knowledge and opinion. The primary importance of knowledge is evident from the fact that knowledge is the umpire of all opinion. We believe in the existence of the ruins of Palmyra and Thebes, and in certain discoveries of algebraists and astronomers. It is our opinion that these things are true, although we may never have visited Palmyra or Thebes, nor made the calculations of the algebraist, nor the observations of the astronomer. In these cases our belief is founded on our experience and knowledge of mankind. It is quite true that travellers exaggerate, and scientific men are sometimes mistaken; but we know that there is always some truth at the bottom of what is communicated by well-meaning writers. More or less, every man's experience assures him of this; and it is the cause of our reliance on the records of history, and the reports of science. Therefore, since all information is made up of knowledge and opinion, plainly knowledge is the one thing which comprises all intelligence.

'Questions of fact,' observes Pascal, in his celebrated 'Provincial Letters,' 'are only to be determined by the senses. If what you assert be true, prove it to be so; if it be not, you labour in vain to induce belief. All the authority in the world cannot enforce or alter belief as to facts; nothing can possibly have power to cause that not to be which actually is.'*

A remarkable instance of the verification of what was assumed to be is related of Pascal by Goodrich. 'Pascal was a philosopher even in childhood. At a very early age he was taught the ten commandments. For several days after, he was observed to be measuring the growth of a blade of grass. When asked the meaning of this, he replied, "The fourth commandment says, 'Six days shalt thou labour, but the seventh is the Sabbath in which thou shalt do no work.' Now I wished to ascertain if nature obeyed this great law, and therefore measured the grass, to see if it grew as much on Sunday as on other days." '**

'We are informed,' says Beattie, 'by Father Malebranche, that the senses were at first as honest faculties as one could desire to be endued with, till after they were debauched by original sin; an adventure from which they contracted such an invincible propensity to cheating, that they are now continually lying in wait to deceive us. But there is in man, it seems, a certain clear-sighted, stout, old faculty, called reason, which, without being deceived by appearances, keeps an eye upon the rogues, and often proves too cunning for them.'***

Though it is so abundantly obvious that the evidences of our senses, internal and external, are, in effect, the sources of all certainty, yet we are not warranted in rejecting, as mere hypothesis, every theory which we cannot at once corroborate. When Euler remarked of his new law of arches, 'This will be found true, though contrary to all experience'—when Gall exclaimed of his new philosophy of the sensorium, 'This is true, though opposed to the philosophy of ages'—they expressed demonstrable truths hidden from the multitude. They announced new generalisations to man. New truths are commonly found to be old unnoted experiences, for the first time subjected to classification, and presented in a scientific form.

To me it seems almost in vain to urge men to notice facts who have never noticed themselves. The truest standards of certainty arise from individuality of retrospection. An intelligent man is, himself to himself, the measure of all things in the universe.

In appealing to the young on the aspiration after improvement, one cannot say 'Consult your aptitudes—follow your bias.' This Is the sole appeal-injunctive to which all natures can respond. But in this half-natured, half-trained, doubtfully-conditioned state of society, though the generous would be incited to noble deeds, the sordid would lay their vulture claws on the world, and the unprincipled victimise their fellows. You have, therefore, to say, 'Man, do what thou listest, provided it be compatible with the welfare of thy fellow men.' Men are not well-natured, and we have thus to guard individuality, and qualify the appeal, and so we miss the soil of great enterprise. Great is the disadvantage. For the fulcrum which is to raise men is without their natures—remote in the wide world.

Man should begin with himself. He loves Truth—it is the first impulse of his nature. He loves Justice—the bandit on the throne, as well as the bandit in the forest, respects justice in some form or other. Man loves Cheerfulness—it is the attribute of innocence and courage. He loves Fraternity—it knits society together in brotherhood. These are standards. His codes of life and judgment arise from these aspirations. That which accords with these principles is reasonable. Whatever develops these principles in conduct is moral. These sentiments are to be confirmed by his own observations. His experience in connection with these rules is the right with which he may examine religions, creeds, books, systems, opinions.

The right understanding of physical and moral facts greatly depends upon intellectual character—and there enters largely into the recondite and ultimate inquiries of intelligent men another class of facts, called mental facts. There is no chance of identifying these without the power of self-analysis, which is one reason why metaphysic ability belongs to so few, and why questions involving metaphysical considerations are such profound enigmas to the majority of the people. The illiterate in these things are easily led or misled by words. They who will not bow before a throne fall prostrate before a sound.

The first principles of things are few. The axioms from which men date their reasoning are chiefly personal. They are expressed in an infinite variety of ways, occasioned by the various conceptions of those who conceive them, and by the different capacities to which they are adapted when offered for the instruction and guidance of others. But this must not mislead us as to the number, and overwhelm us with a sense of complexity, where in fact simplicity reigns. Those who have the power of self-analysis make for themselves rules of conduct, and the best are originated in this way—for when a man recasts his acquirements of sense and education, in order to see on what all rests, and what are essential standards of action and judgment, he resolves all into few, and those the clear and strong. Rob Roy's self-examination paper is presented to us in those lines which Sir Walter Scott, with grace and justice, characterised as the 'high-toned poetry of his gifted friend Wordsworth.'

Sir Walter Scott himself has enforced the same views:—'How much do I need such a monitor,' said Waverley to Flora. 'A better one by far Mr. Waverley will always find in his own bosom, when he will give its still small voice leisure to be heard.

To awaken the senses and instruct them and direct them aright in the art of observation, is a great and essential undertaking. All scattered aids need collecting together. De la Beche in 'Geology,' and Miss Martineau have written books, entitled 'How to Observe.' This quality is the distinction between the natural and artificial man—the natural man observes what is in nature—the artificial notes what he finds in books—the one depends on himself—the other on an encyclopaedia. We want contrast, in order to know as well as to explain. Foreigners observe us better than we observe ourselves. The common escapes our attention. To know a fact fully we seek its opposite to compare it with.

Were men reared with the powers of men without the genius of the child being impaired, the ability to observe would be more general and perfect among us. Children stop at everything to question its nature, at every word to ask its import. It was the aim of Pestalozzi to cultivate by his system of tuition this incessant questioning. But parents among the poor know not the value of the habit, or knowing it have not time to gratify it, and thus this happiest aptitude of childhood is repressed.

With regard to the analysis of groups of facts, Mr. J. S. Mill remarks—'The observer is not he who merely sees the thing before his eyes, but he who sees what parts that thing is composed of. To do this well is a rare talent. One person from inattention, or attending only in the wrong place, overlooks half of what he sees; another sets down much more than he sees, confounding it with what he imagines, or with what he infers $ another takes note of the kind of all the circumstances, but being inexpert in estimating their degree, leaves the quantity of each vague and uncertain; another sees indeed the whole, but makes such an awkward division of it into parts, throwing things into one mass which require to be separated, and separating others which might more conveniently be considered as one, that the result is much the same, sometimes even worse, than if no analysis had been attempted at all.'*

In the case of the Leigh Peerage there was a number of witnesses examined in the House of Lords, as to the existence of a certain monument in Stonely Church—'The first witness described the monument as being black; the second spoke of it as a kind of dove-colour; the third said it was black and white; the fourth said it was originally white, but dirty, when he saw it; the fifth differing from the others, said it was blue; the next witness described it as a light marble, but said it had a dark appearance as if it had been bronzed, and the last witness spoke of it as feeing of a light grey colour. Then, as to the form of the monument, the first witness said it was oblong; the next said it was square at the top, and came down narrower to the bottom, and there rested on a single truss; the third witness described it as being square at the bottom, testing upon two trusses; and went up narrower and narrower to a point at the top; the fourth witness said it was angular at the top; the next said it was square at the bottom, was brought to a point in the middle, and was then curved into a sort of festoon; the sixth witness stated that it was square at the top and bottom, and had a curve; and the last said it was square at the top and bottom. As to the language of the inscriptions, the first witness stated that the names of Thomas and Christopher Leigh were in English; the next said the inscription was not in English; the third said there was a great deal in English; the fourth witness said the whole, (with the exception of the name Christopher Lee), was in a language, which he did not understand; the next witness stated that the inscription was all in English, except the words Anno Domini; and the last witness said it was not in English.'*

All these witnesses agree as to the fact in dispute, but their variances in testimony illustrate the common inattention of observation—and this case farther admonishes us that if such differences may exist as to a question of fact, where the senses are the same, little wonder that differences exist as to matters of opinion, where intellectual capacity and information are so various.

We know from experience that the sportsman sees a point which is hidden from the unpractised aimer—the painter sees traits of character of light and shade in an object which the untaught limner never observes; the musician distinguishes harmonies and discords that fall unnoted on the uneducated ear.

Thus we learn that by cultivation we can increase natural susceptibility to observe.

The extent is surprising to which the unanalytic are in ignorance of the real nature of phenomena. 'There is nothing which we appear to ourselves more directly conscious of, than the distance of an object from us. Yet it has long been ascertained, that what is perceived by the eye, is at most nothing more than a variously coloured surface; that when we fancy we see distance, all we really see is certain variation of apparent size, and more or less faintness of colour.'*

In preparing to support an argument on any question, we must first determine the sources whence the facts are to be collected. Instance: The objects of municipal laws are rights and crimes.

This outline of the investigation prosecuted, the inquirer next consults the authors who treat of the rules which are applied for determining the facts of public consent, testimony, records, confessions: he is then able to support his own argument in a valid manner, or prepared to examine the facts offered by an opponent in support of an opposite view.

The opinion may be hazarded that it is not so much from want of capacity to observe that error arises, as from the want of conviction that we should observe well before we attempt to infer. Nature is inventive, and desire, once awakened, will, without formal rules, find out a thousand modes of gratification. The foundation for a soldier logic than now prevails will be laid when the people are impressed with the great importance of looking well to facts as the data of all inferential truth.

There is a noted aphorism of Cendillac, to the effect that the one sufficient rule for discovering the nature and properties of objects is to name them properly, as if, observes Mr. J. S. Mill, 'the reverse was not the truth, that it is impossible to name them properly except in proportion as we are already acquainted with their nature and properties.' Need it be added that this knowledge is only to be had by patient observation?

To assist this habit, Dr. Watts recommends the thinker to ascertain if a given idea is clear and distinct, obscure and confused, learned or vulgar, perfect or imperfect, adequate or inadequate—true or false. 'View a subject, says he, as through a telescope, so as to command a clear view of it; examine its whole bearings as you look over a globe; consider it in its several properties—anatomise it as with a scalpel. Take cognizance of its various aspects as though inspecting it through a prismatic glass. Whenever we contemplate a single object in nature is obvious it must have duration, size, weight, form, colour, such qualities being essentially present in all adequate conceptions of physical phenomena.'

It was objected to the 'Cricket' of Mr. Dickens, that his delineation of Bertha was wanting in truthfulness. The teachers of the blind who knew their nature could detect the departure from the reality of their habits in the sketch of Bertha. The study of the blind was necessary to insure success. We may not be able in any one book to give rules for the study of all subjects, but we may indicate that we ought not to speak of what we do not know, and that if we mean to introduce certain facts into our speech or writing, we should consult the records and experienee of those persons who are known to have written upon the subject, and follow the best directions they give, and we shall generally attain accuracy.

Mr. Combe observes, in his introduction to his notes on the United States of North America, p. xi.—'I was told that a certain person boasts of having given Miss Martineau erroneous information for the purpose of leading her into mistakes; and another in Philadelphia assures his friends that he "crammed" Capt. Marryatt with old "Joe Millers," which the Capt. embodied into his books as facts illustrative of American manners. This seems to be a case in which some uncertainty must ever exist as to the value of the facts collected by travellers. They cannot observe all, or test half that they do observe. They must rely on testimony. But they might do this—They might tell us precisely the kind of authority they followed, and then the reader could form some opinion of the value of what was communicated. Had Miss Martineau and Captain Marryatt given the name and addresses of their informants, the latter would now be punished by being infamously known throughout Europe; and all future travellers warned from them—and all future informants warned by their example. Where informants cannot be mentioned by name and address, the chances are, they cannot be trusted. When first connected with public proceedings, I found myself made the depository of innumerable bits of scandal, and ominous reports of public characters. To all who told me anything, if I attached importance to it, I made it a rule to ask—'May I mention it to the party with your name?' 'O, no, I would rather not,' was the common reply. To all written communications answer—'Please add your name and address—and may I publish them if occasion requires?' 'O, no, don't,' would be the general injunction. Thus I found that huge reports, inflated as balloons, shrunk like them when pricked by the pin of a question—'Will you answer for it?' Thus I saved myself from being imposed upon by, or being the retailer of, reports for which the originator or relator would not or could not vouch.

'Upwards of twenty years ago,' says George Combe, 'I accompanied a member of the bar of Paris, a philosopher and a man of letters, on a visit to the Highlands of Scotland. At Callendar a boy of twelve or thirteen years of age attended as a guide to some interesting spot, and in external appearance he seemed to be in every respect one of the common lads of the village. My Parisian friend entered into conversation with him; asked him if he had been at school, and soon discovered that to a tolerable acquaintance with the Greek and Latin languages, he added a pretty extensive-knowledge of arithmetic and geography, and was then engaged in the study of mathematics. My friend conceived that the boy was an average specimen of the peasantry of the country; and greatly admired the educational attainments of the Scotch people, which he had previously heard highly extolled. But,' adds Mr. Combe, 'the boy was the natural son of an English officer, who had resided in the neighbourhood, and who, while he ordered him to be reared in the hardy habits of the Scottish Highlanders, had provided ample funds for his mental education.'*

It is difficult to believe in this Frenchman being a 'philosopher, making, as he did, a national induction from a single instance. Had he previously inquired, as he ought to have done, the particulars of that lad's life and rearing, before coming to so large a conclusion, he would at once have discovered the error he was falling into.

In the Registrar General's Report of 1840, the mean of married persons unable to write is presented. The conclusion is based upon the statistics of nine counties. But when it was found that only three per cent, of the persons marriageable, did marry, the datum was found insufficient to afford sure results. This fact; is given by Mr. Combe in the same book. Then how many boys ought our 'philosopher' to have questioned before making his vast inference?

Another instance of the value of a question I extract from the same work. Mr. Combe says:—'A few years ago, when travelling in Somersetshire, I saw four horses, attended by two men, drawing a light plough in a light soil. "What a waste of labour is here," said I to an intelligent farmer; "in Scotland, two horses and one man will accomplish this work." "We rear and train young horses for the London market," said he; "two of the four which you see are serving an apprenticeship to labour."' Had Mr. Combe asked a few questions as to the correctness of his assumed inference, he would have been saved from his erroneous conclusion. We should be wary of unquestioned data.

When Murray's Grammar was first placed in my hands, I found in it certain references to the Canons of Language in the larger edition. I questioned my teacher as to what it meant. 'It is a trick of the printer,' he answered, 'to induce you to buy the larger volume.' I do not believe this now. I believe that it was a necessary reference. An author who has written upon a given subject, naturally finds his own ideas coincident illustrations of his views, and honestly refers to them. In this book I have made a few references to previous works of mine, and it has struck me that nine ont of ten of the readers will set this down to artifice or egotism. Yet it is neither. I have referred only to avoid the full quotation of some necessary illustration of the argument. Yet few will penetrate to the fact, and most will be apt to infer a trick from appearances.