Defence of monism—Pure and applied science (theoretic and practical reason)—Pure (theoretical) sciences: physics, chemistry, mathematics, astronomy, geology; biology, anthropology, psychology, philology, history—Applied (practical) sciences: medicine, psychiatry, hygiene, technology, pedagogics, ethics, sociology, politics, jurisprudence, theology—Antinomy of the sciences—Rational and dogmatic disciplines—Correlation of the sciences—Faculties—Reform of education—The ideal world—Harmony of monism.

Now that we have reached the end of our long journey, we may take a general survey of the path we have pursued, and say how far we owe our progress to the monistic philosophy. In doing so, we shall at once justify our own point of view and indicate the relation of biology to the other sciences. I feel the more bound to do this as the present volume is not only a necessary supplement to the Riddle, but at the same time my last philosophic work. At the end of my seventieth year I would supply some of the defects of the Riddle, answer some of the most stringent criticisms directed against it, and as far as possible complete the philosophy of life at which I worked for half a century.

In inviting my readers to accompany me once more through the broad domain of the monistic philosophy I must, as their modest guide, show scientific justification at the narrow entrance—produce, so to say, the ticket of admission to this investigation. The academic philosophy which still controls the German universities watches every door with jealous eyes, and has an especial concern to keep out modern biology. Official German philosophy is still for the most part taken up with a mediÆval metaphysic and the dualism of Kant, the openly dogmatic character of which it greets as "criticism." In the course of the forty years during which I have taught as ordinary professor of zoology at Jena I have had occasion to assist at several hundred examinations of doctors, teachers, etc., in which distinguished representatives of philosophy were examiners. I saw that nearly always the chief stress was laid on a kind of conceptual gymnastics and self-observation, and on the correct knowledge of the innumerable errors which the (mainly dualistic) leaders of ancient and modern philosophy have left us in their vast literature. The central feature of the whole scheme is Kant's theory of knowledge, the defects and one-sidedness of which I have treated in the first and nineteenth chapters. In psychology a most extensive knowledge of psychic powers on the basis of the introspective method is demanded; the physiological analysis of the "soul" and the anatomic study of the phronema are carefully avoided, as are also the comparative and genetic study of the mind. Many of our metaphysicians go even farther and regard philosophy as a separate science—a sublime "mental science," quite independent of the common empirical sciences. One is tempted to quote the saying of Schopenhauer: "It is a sure sign of a philosopher that he is not a professor of philosophy." In my opinion, every educated and thoughtful man who strives to form a definite view of life is a philosopher. As queen of the sciences, philosophy has the great task of combining the general results of the other sciences, and of bringing their rays of light to a focus as in a concave mirror. The various tendencies of thought that arise in such numbers have all a right to scientific respect and discussion, the monistic minority no less than the dualistic majority. We have to inquire, then, how far monism has succeeded in gaining firm foothold in the various fields of science, and we may begin with a distinction between pure (theoretical) and applied (practical) science.

Pure philosophy aims at a knowledge of the truth by means of pure reason, as I explained in the first chapter. However, this theoretical philosophy finds itself in most of the sciences in direct and frequently important relations to practical life, and so in the form of applied philosophy becomes a weighty factor in civilization. In this the real claims of practical life are often in contradiction to the ideal tenets of the scientifically grounded theory. In such cases, in my opinion, the pure pursuit of the truth must take precedence of applied philosophy. I thus dissent entirely from the view of Kant, who expressly gives precedence to practical reason, and subordinates theoretical reason to it. Kant's error was fated to have a terrible influence, because the dominant authorities in Church and state eagerly embraced it to insure everywhere the supremacy of the dogmas of practical reason over the attainments of pure critical reason.

From the point of view of natural monism we may take physics in the wider sense as the fundamental science. The term physis (the Greek equivalent of the Latin "nature"), in its original meaning, comprises the whole knowable world—Kant's mundus sensibilis. His supersensual or "intelligible" world is, on his own definition, the object of faith, not knowledge. It is very remarkable to find a thinker like Kant contradicting himself already in his fundamental distinction of the two worlds. How can the supersensual world, with its three central mysteries (God, freedom, and immortality), be described as intelligible (i.e., knowable) when it is proved by pure reason that the human mind is incapable of knowing it, or of forming any positive or negative idea of it? Lucus a non lucendo! We may, therefore, leave this supernatural metaphysical world to faith and fiction, and confine our studies to the real physical world, nature. The idea of physics as a comprehensive natural philosophy, as it was conceived in classic Greece, has been more and more restricted in the course of time. To-day it is generally taken to mean the science of the phenomena of inorganic nature, their empirical determination by observation and experiment (experimental physics), and their reduction to fixed natural laws and mathematical formulÆ (theoretical or mathematical physics). Of late a distinction has been drawn between the physics of mass and the physics of ether; the one deals with mechanics, the movement and equilibrium of ponderable matter, of solid, fluid, and gaseous bodies (statics and dynamics, gravitation, acoustics, meteorology); the other is occupied with the phenomena of ether (or imponderable matter) and its relations to mass (electricity, galvanism, magnetism, optics, and calorics). In all these branches of inorganic physics the monistic view is now generally received, and all attempt at dualistic explanation abandoned.

The vast department of chemistry, which has now become so important both for theoretical and practical purposes, is really only a part of physics. But while modern physics restricts itself to the study of inorganic forms of energy and their conversions, chemistry, as the science of matter, takes up the study of the qualitative differences between the various kinds of ponderable matter. It divides ponderable bodies into some seventy-eight elements, the relations of which to each other have been determined in the periodic system of the elements, and their probable common origin from some primitive matter (prothyl) been shown. The constant features of chemical combinations which have been established by the analysis and synthesis of the elements, and especially the law of simple and multiple proportions discovered in 1808, led to the empirical determination of the atomic weight of the elements and to the chemical theory of the atom. The acceptance of these atoms (as space-filling separate particles of matter—however we may regard them in other respects) is an indispensable hypothesis in chemistry, like the hypothesis of the molecule in physics. Modern dynamism (or energism) is wrong when it thinks it can dispense with these hypotheses and replace the atoms by the notion of immaterial non-spatial points of force. However, in both the dynamic and the material school monism is retained in every department of chemistry.

Modern science considers the ultimate aim of all research to be the exact determination of phenomena in measure and number, or the reduction of all general knowledge to mathematically formulated laws. As the great Laplace established his system mathematically, it has lately been claimed that a comprehensive (ideal) Laplace-mind could embrace the whole past, present, and future of the universe in a single gigantic mathematical formula. Kant has expressed this exaggerated estimate of mathematics in the phrase: "Every science is only true science in proportion as it is amenable to mathematical treatment"; and to this he has added the second error that the mathematical axioms (being necessary and universal truths) belong to the a priori constitution of the mind, and are independent of experience (a posteriori). However, John Stuart Mill and others have shown that the fundamental ideas of mathematics are acquired originally, like those of any other science, by abstraction from experience; and the modern phylogeny of the mind has confirmed this empirical view. We must remember, moreover, that mathematics deals only with quantitative relations in time and space, and not with the qualitative features of bodies. In fact, Kant himself showed that mathematics only answers for the absolute formal correctness of conclusions it draws from given premises, and has no influence on the premises themselves. Hence, when we examine the abstract thinking-power of the phronema in its mathematical operations physiologically and phylogenetically, we find that even this "exact fundamental science" is only accessible to pure monism and excludes all dualism. The great regard which mathematics enjoys as an exact science in all branches of knowledge is chiefly due to its formal accuracy, and to the possibility of expressing infallibly spatial and time quantities in number and mass.

Astronomy is one of the older sciences that took definite shape thousands of years ago, and received a solid mathematical foundation. Observations of the movements of the planets and eclipses of the sun were conducted by the Chinese, Chaldeans, and Egyptians several thousand years before Christ. Christ himself had no more suspicion of these great cosmological discoveries than of the systems which the Greek natural philosophers had built up three hundred to six hundred years before his birth. After Copernicus had destroyed the geocentric system in 1543, and Newton had provided a mathematical basis for the new heliocentric system by his theory of gravitation in 1686, cosmogony was firmly established in a monistic sense by the General Natural History of the Heavens of Kant, and the MÉcanique CÉleste of Laplace. Since that time there has been no question of the conscious action of a Creator in any part of astronomy. Astrophysics has enlarged our knowledge of the physical features, and astrochemistry (by means of spectrum analysis) of the chemical nature of the other heavenly bodies. The monism of the physical universe has now been established.

Geology was not developed into an independent science until towards the end of the eighteenth century, and did not extinguish the earlier notion of the creation of the earth until after 1830, when the principle of continuity and evolution was established. The oldest part of the science is mineralogy; the great practical value of the rocks, and especially the metals obtained from them, having appealed to man's interest thousands of years ago. In the Stone Age, Bronze Age, Iron Age, etc., the material for weapons and tools was provided by stone and metal. Afterwards the development of mining led to a closer acquaintance with these metals. But no notice was taken of the fossil remains of animals and plants until the close of the Middle Ages. It was not until the eighteenth century that students began to perceive the great significance of these "creation-medals," and at the beginning of the nineteenth paleontology arose as an independent science, and proved equally important to geology and biology. Other branches of geology, such as crystallography, have also made considerable progress during the last half-century, with the aid of physics and chemistry. All these sections of geology, especially geogeny, or the science of the natural development of the earth, are now recognized to be purely monistic sciences.

In the five branches of science I have enumerated, pure monism has been universally and exclusively admitted (as far as they relate to inorganic nature) in the second half of the nineteenth century. There is no question in them to-day of the wisdom and power of the Creator. This is equally true of geology, astronomy, mathematics, chemistry, and physics. It is otherwise with the remaining sciences which deal with organic nature; in these we have not yet succeeded in giving a physical explanation and mathematical formulation of all phenomena. Hence vitalism enters with its dualistic notions, and splits the science into two different branches—natural science (physics in the wider sense) and mental science (metaphysics); fixed natural laws are supposed to rule only in the former, while in the latter we still have the "freedom" of the spirit and the supernatural. This applies, first of all, to biology in the broadest sense (including anthropology and all the sciences that relate to man). In the preceding chapters of biological philosophy we have sought to refute vitalism in every form, and to secure the exclusive acceptance of monism and mechanicism in every branch of the science of life.

Anthropology is still, as it has been for centuries, taken in many different senses. In the widest sense, it embraces the whole vast science of man, just as zoology (in my opinion) deals with all parts of the animal world. Since I regard anthropology as a part of zoology, I naturally extend the principles of monism to both. However, this general monistic conception of the science of man has met with only a restricted acceptance up to the present. As a rule, the term "anthropology" is restricted to the natural history of man, which includes the anatomy and physiology of the human organism, embryology, prehistoric research, and a small part of psychology. But this "official anthropology," as most of our anthropological societies (especially in Germany) conceive it, generally excludes phylogeny, the greater part of psychology, and all the mental sciences, which are regarded as metaphysical in the narrower sense. I endeavored to show in my Anthropogeny thirty years ago that man (as a placental mammal of the order of primates) is no less unified an organism (with body and soul) than any other vertebrate, and that, therefore, every aspect of his being should be dealt with monistically.

As is well known, the views of experts and laymen alike are very much divided as to the place of psychology in the scheme of the sciences. The great majority of the professional psychologists, and of educated people generally, adhere still to the antiquated dogma, with its religious foundation, that man's soul is immortal and an independent immaterial entity. This dualistic view has been supported in the schools especially by the authority of Plato, Descartes, and Kant; in religion by the authority of Christ, Paul, and Mohammed; in education and the state by the authority of most governments; and in physiology by most of the older, and even some recent, physiologists. On this view, psychology is a special mental science, having only an external and limited connection with natural science. But modern comparative and genetic psychology, the anatomy and physiology of the brain, have, in the course of the last forty years, established the monistic view that psychology is a special branch of cerebral physiology, and that therefore all its parts and their application belong to this section of biology. The soul of man is a physiological function of the phronema. As I have fully explained the monistic conception of psychology in chapters vi.-xi. of the Riddle, and supported it with all the arguments of anatomy, physiology, ontogeny, and phylogeny in my Anthropogeny, I need not go further into the subject.

The science of language shares the fate of its sister, psychology; by one section of its representatives it is taken monistically as a natural science, and by another section it is dualistically conceived as a branch of mental science. On the old metaphysical view, speech was regarded as an exclusive property of man, either a gift of the gods or an invention of social man. But in the course of the nineteenth century the monistic and physiological position that speech is a function of the organism, and has been gradually developed like all other functions, has been established. The comparative psychology of the higher animals showed that in various classes the thoughts, feelings, and desires of the gregarious animals are communicated partly by signs or touch, partly by sounds (the chirrup of the cricket, the cry of the frog, the whistle of many reptiles, song of birds and singing-apes, roaring of carnivora and ungulates, etc.). The ontogeny of speech showed that its gradual development in the child is (in accordance with the biogenetic law) a recapitulation of its phylogenetic process. Comparative philology taught that the languages of the different races have been formed polyphyletically, or independently of each other. The experimental physiology and pathology of the brain showed that a definite small region of the cortex (the Broca fissure) is the centre of speech, and that this central organ, in conjunction with other parts of the phronema and the larynx (the peripheral organ), produces articulate speech.

Historical science is, like philology or psychology, still conceived in different senses by experts. Very often history is wrongly taken to mean the record of events that have occurred in the course of the development of civilized life—the history of peoples and states (humorously described as "the history of the world"), of civilization, of morals, etc. This is merely an anthropocentric feeling that in the strictly scientific sense "history" can only be used for the record of man's doings. In this sense history is opposed to nature, the one dealing with the province of morally free phenomena (with preconceived aim), and the other comprising the province of natural law (without preconceived aim). As if there were no "natural history," or as if cosmogony, geology, ontogeny, and phytogeny were not historical sciences! Although this dualistic and anthropistic view still prevails in our universities, and state and Church protect the venerable tradition, there can be no doubt that sooner or later it will be replaced by a purely monistic philosophy of history. Modern anthropogeny shows us the intimate connection between the evolution of the human individual and that of the race; and by means of prehistoric and phylogenetic research it joins what is called the history of the world to the stem-history of the vertebrates.

Medicine belongs to the front rank of practical or applied sciences. In its long and interesting history it teaches how it is only a monistic knowledge of nature, not a dualistic notion of revelation, that affords the foundations of true science and the profitable application of this to the most important aspects of practical life. Medicine was originally the business of the priests, and for thousands of years it was under the influence of mystic and superstitious ideas which were connected with religious dogmas. However, two thousand years ago the great physicians of classic antiquity made a serious effort to provide a solid base for medical practice by a thorough anatomic and physiological study of the human frame. But in the general reaction of the Middle Ages superstitious and miraculous ideas once more defeated independent scientific investigation. Disease was supposed to be the work of evil spirits (as Christ thought) which had to be exorcised. Miracles are still thought to take place, even in cultured circles. I need only mention the wonders of patent medicines, magnetic cures, Christian Science, and other charlatanry. However, the great development of science in the nineteenth century, especially the astonishing advance of biology about the middle of the century, gradually shaped medicine into the monistic science which assuages so much pain and suffering in humanity to-day. Pathology, the science of disease, and therapeutics, the rational science of healing, are grounded now on the safe methods of physics and chemistry and a thorough knowledge of the human organism. Disease is no longer regarded as a special entity that comes on the body like an evil spirit or mysterious organism, but is conceived as a baneful disturbance of its normal activity. Pathology is only a branch of physiology; it studies the changes that take place in the tissues and cells under abnormal and dangerous conditions. When the causes of these changes are poisons or foreign organisms (such as bacteria or amoebÆ), the art of healing has to remove them and restore the normal equilibrium of the functions.

The science of mental disease is a special branch of medicine; it has the same relation to it as psychology has to physiology. However, as pathological psychology it deserves special consideration, not only on account of its extreme practical importance, but also because of its theoretical interest. The misleading dualist idea of body and soul that has perverted our notions of mental life from the oldest times has led people to regard mental disorders as special phenomena, at one time directly as evil spirits that enter from without into the human body, at another time as mysterious dynamic occurrences affecting the mystic being of the soul (independently of the body). These dualistic and still wide-spread and mischievous errors have caused the most fatal mistakes in the treatment of mental disease; they have had the most unfortunate effect on juristic and social and other aspects of practical life. But the ground has been cut from under these irrational and superstitious ideas by modern psychiatry, which regards all mental disease as a disorder of the brain, and traces it to changes in the cortex that lie at the root of all psychoses (delusions, lunacy, etc.). As we call this central organ of mind the phronema, we may say: Psychiatry is the pathology and therapeutics of the phronema. In many disorders we have already succeeded in anatomically and chemically tracing the changes in the psychic or phronetal cells (the neurona in the phronema). These acquisitions of the pathological anatomy and physiology of the phronema have a great philosophic interest, because they throw a good deal of light on the monistic conception of psychic life. As the greater part (sixty to ninety per cent.) of these diseases are hereditary, and they have mostly been acquired gradually by the ancestors of the patient, they also afford clear proof of progressive heredity, or the inheritance of acquired characters.

Thousands of years ago, when barbaric races began to adapt themselves to civilized life, they had a concern for their bodily health and strength. In classic antiquity the care of the body by baths, gymnastic exercises, etc., was greatly developed, and connected with religious ceremonies. The splendid aqueducts and baths of Greece and Rome show how much importance they attached to the external and internal use of water. The Middle Ages brought reaction in this province like so many others. As Christianity depreciated this life and said it was merely a preparation for the life to come, it led to a disdain of culture and of nature; and as it regarded man's body only as the temporary prison of his immortal soul, it attached no importance to the care of it. The frightful plagues that swept away millions of men in the Middle Ages were only fought with prayer, processions, and other superstitious devices, instead of with rational hygienic and sanitary measures. We have only gradually learned to discard this superstition. It was not until the second half of the nineteenth century that a sound knowledge of the physiological functions and environment of the organism induced people once more to have a concern for bodily culture. All that modern hygiene now does for the public health, especially the improvement of the dwellings and food of the poorer classes, the prevention of disease by healthier habits, baths, athletics, etc., can be traced to the monistic teaching or reason, and is altogether opposed to the Christian belief in Providence and the dualism connected therewith. The maxim of modern hygiene is: God helps those who help themselves.

The remarkable progress of technical science in the nineteenth century, which has stamped our age as "an age of machinery," is a direct consequence of the immense advance of theoretical science. All the privileges and comforts which modern life gives us are due to scientific discoveries, especially in physics and chemistry. We need only recall the enormous importance of steam and electric machinery, modern mining, agriculture, and so on. If by these means modern industry and international commerce have prospered beyond all expectations, we owe this to the practical application of empirical truths. "Mental science" and metaphysical speculation have had nothing to do with it. There is no need of further proof that all the technical sciences have a purely monistic character, like their exact sources, physics and chemistry.

The scientific development of education is one of the greatest tasks of modern civilization. The ideas that are impressed on the mind in early youth are most persistent, and generally determine the direction of thought and conduct for the whole of life. Hence we find the struggle between the two philosophic tendencies assuming the greatest practical importance in this department. As the priests were, thousands of years ago, in the first stages of civilization, the sole trainers of the growing mind, they had charge of the school as well as of medicine. Religion was made the chief foundation of instruction, and its doctrines were the moral guide for the whole of life. The isolated attempts that were made by monistic philosophy in ancient times to destroy this theistic superstition had no effect on the education of the young. In this the dualistic principles of Plato and Aristotle prevailed, their metaphysical theories being blended with the teaching of the Church. In the Middle Ages the power of the Roman priesthood enforced them everywhere. And, although a good deal of this teaching lost its prestige at the Reformation, the influence of the Church on the school was maintained down to our own time. The spiritual power of the Church finds a useful ally in this in the conservative attitude of most governments. Throne and altar support each other; both dread the advance of scientific inquiry. In face of this powerful dualistic alliance, supported by the mental apathy of the masses and a convenient blind submission to authority, the monistic system has a difficult position to maintain. It will only gain solid ground in education when the school is divorced from the Church and scientific knowledge is made the foundation of the curriculum. I have pointed out in the nineteenth chapter of the Riddle the guiding principles to be followed in this reform of education in opposition to the influence of Church and state.

As we have dealt in the eighteenth chapter with morals and their development from habit and adaptation, we need only mention here the contradiction that we still find between the monistic claims of pure reason and the dualistic claims of practical reason. This has been largely sustained by Kant's teaching, but his categorical imperative has been completely refuted by modern science. The metaphysical grounding of morality on free will and ethical intuitions (a priori) must be replaced by a physiological ethic, based on monistic psychology. As this can no more recognize a moral order of the world in history than a loving Providence in the life of the individual, the monistic morality of the future must be reducible to the laws of biology, and especially of evolution.

The great importance that attaches to the new science of sociology is due to its close relations to theoretical anthropology and psychology on the one hand, and to practical politics and law on the other. When we take it in the wider sense, human sociology joins on to that of the nearest mammals. The family life, marriage, and care of the young in the mammals, the formation of herds in the carnivora and ungulates and of troops in the social apes, lead on to the looser associations of savages and barbarians, and from these to the beginnings of civilization. The history of these associations is connected with the social rules that govern the intercourse of smaller and larger communities. In the biological reduction of social rules to the natural laws of heredity and adaptation, dynamic sociology (as Lester Ward has called it) proceeds on purely monistic lines, while in social intercourse itself we still find a good deal of dualism. How little truth and nature count for in our cultured society, how much hypocrisy and insincerity have to do with social rules, has been well shown by Max Nordau in his Conventional Lies of Civilization.

Politics is closely connected with sociology on the one hand and law on the other. As internal politics it controls the organization of the state by a constitution; as external or foreign politics it directs the relations of states to each other. In my opinion, pure reason should prevail in both departments; the relations of the citizens to each other and to the whole should be regulated by the same ethical principles that we recognize in personal intercourse. We are, unfortunately, very far from this ideal in the life of a modern state. Brutal egoism rules in foreign politics; every nation thinks only of its own advantage, and furthers it with all its military and other resources. Domestic politics is still largely directed by the barbaric prejudices of the Middle Ages. Great struggles are in progress between the central government and the mass of the people. Both parties spend themselves in fruitless conflicts; yet reason in the life of the state suffers more than its special political complexion. "Whether the state shall be a monarchy or a republic, aristocratic or democratic, are subordinate questions. The great question is: Shall the modern state be spiritual or secular? Shall it be governed theocratically by irrational beliefs and clerical arbitrariness, or nomocratically by rational laws and civic right?" (Riddle, chapter i.).

In the science of law, too, we find the prevalence of the dualistic principles that have come down from the Middle Ages and antiquity, and have acquired a certain sacredness by blending with the teaching of the Church. Kant's dualism is again found to be at work, influencing the ideas of jurists and statesmen. With it we find in our codes many carefully preserved relics of mediÆval superstition. A great deal of harm is done by this religious influence. Every day we read in the papers of curious deliverances in the lower and higher courts at which every thoughtful man can only shake his head. Here also there will be no solid improvement until the education of jurists includes a thorough training in anthropology and psychology as well as in the code.

Theology has stood at the head of the four venerable "faculties" at our universities for centuries. It still holds this place of honor, as the Church, the organ of practical theology, continues to exercise a profound influence on life. In fact, most of the other branches of applied science—especially jurisprudence, politics, ethics, and pedagogics—are still more or less affected by religious prejudices. The chief of these is the idea of God conceived in some form or other as the Supreme Being; as Goethe says, "Every one calls the best he knows his God." However, the idea of God is not the chief feature of all religions. The three greatest Asiatic religions—Buddhism, Brahmanism, and Confucianism—were at first purely atheistic; Buddhism was at once idealistic and pessimistic, whence Schopenhauer regarded it as the highest of all religions. On the other hand, belief in a personal God is the central feature of the three great Mediterranean religions. This anthropomorphic God is conceived in a hundred forms in the various sects of the Mosaic, Christian, and Mohammedan religions, but his existence remains one of the chief articles of faith. No evidence of his existence is to be found; this was very ably shown by Kant, although he thought that practical reason postulated it. All that revelation is supposed to teach us on the matter belongs to the region of fiction. The whole field of theology, especially dogmatic theology, and the whole of the Church teaching based on it, are based on dualistic metaphysics and superstitious traditions. It is no longer a serious subject of scientific treatment. On the other hand, comparative religion is a very important branch of theoretical theology. It deals with the origin, development, and significance of religion on the basis of modern anthropology, ethnology, psychology, and history. When we study without prejudice the results of these sciences bearing on religion, theology turns out to be pantheism, in the sense of Spinoza and Goethe, and thus monism becomes a connecting link between religion and science.

This brief survey of the twenty chief branches of modern science and their relation to monism and dualism shows that we are face to face with great contradictions, and that we are still far from the harmonious and successful adjustment of these differences. They are partly due to a real antinomy of reason in the Kantist sense—an antithesis in ideas, in which the positive seems to be just as capable of proof as its contradictory. But, for the most part, this unfortunate antinomy in the sciences is connected with their historical development. Pure reason, the highest quality of civilized man, was gradually evolved from the intelligence of the savage, and this in turn from the instincts of the apes and lower mammals; and many relics of its former lower condition remain to-day, and have, through practical reason, a most prejudicial influence on science. These dualistic prejudices and irrational dogmas—intellectual residua of the primitive condition of the race, fossil ideas and rudimentary instincts—still pervade the whole of modern theology, jurisprudence, politics, ethics, psychology, and anthropology. If we glance at the whole field of modern science at the beginning of the twentieth century in this connection, we can distribute its twenty sections into three groups—rational (purely monistic), semi-dogmatic (half-monistic), and dogmatic (predominantly dualistic) disciplines.

The following may be classed as rational or purely monistic sciences, in which no competent and thoroughly expert representative now admits dualistic considerations: of the pure or theoretical sciences, physics, chemistry, mathematics, astronomy, and geology; of the applied or practical sciences, medicine, hygiene, and technology. On the other hand, in the semi-dogmatic sciences we still find a mixture of monistic and dualistic ideas in the appreciation of their aims and objects, one or the other prevailing according to the party position or personal training of the individual representative. This is the case with most of the biological sciences, biology (in the broadest sense), anthropology, psychology, philology, history, psychiatry; and of the applied sciences, pedagogics and ethics. The two latter sciences form a transition to the four purely dogmatic sciences in which the traditional dualism is still paramount: sociology, politics, jurisprudence, and theology. In these branches of science mediÆval traditions retain a good deal of their power. Most of their official representatives cling to prejudices and superstitions of all sorts, and very slowly and gradually admit the acquisitions of pure reason as embodied in monistic anthropology and psychology. The intellectual life was in many respects more advanced at the beginning of the nineteenth than of the twentieth century.

This classification of the chief branches of knowledge in their relation to philosophy, the comprehensive science of general truths, is naturally only a provisional and personal sketch. It is especially difficult from the circumstance that all the sciences have very complex relations to each other, and have undergone many changes as to their aims and subjects in the course of their historical development. I will only point out that a good deal of science—in fact, the rational sciences with exact mathematical basis—have now been completely won over to monism; and in the semi-dogmatic sciences it is gaining ground from day to day, so that we may hope sooner or later to see the four dogmatic sciences also, the strong bulwarks of dualism—sociology, politics, jurisprudence, and theology—succumb to monism. For the ultimate aim of all the sciences can only be the unity of their underlying principles, or their harmonious unification by pure reason.

It is now more and more generally acknowledged in educated countries that a complete reform of our educational curriculum is needed, both in elementary and secondary schools and at the universities. The great struggle between two different tendencies assumes larger proportions every day. On the one hand, most governments, following their conservative instinct, cling as far as possible to mediÆval traditions, and find support in the dogmatic teaching of theology and jurisprudence. On the other hand, the representatives of pure reason seek to get rid of these fetters, and to introduce the empirical and critical methods of modern science and medicine into what are called the mental sciences. The opposition between the two parties is accentuated by their different sociological tendencies. Liberal humanists claim that the freedom and education of all men is the aim of progressive evolution, in the conviction that the free development of the personality of each individual is the surest guarantee of happiness. To conservative governments this is a matter of indifference; they look on the individual citizens, in accordance with the manifold division of labor, merely as so many screws and wheels in the great organism of the state. The "upper ten thousand" naturally think of their own welfare first, and desire to keep all higher education to themselves. But in the light of pure reason the state is not an end in itself; it is a means to insure the prosperity of the citizens. To each of these, whatever their condition, the opportunity should be afforded of acquiring the higher education and developing their talents. Hence in education we should impart a general outlook on all the sides of human life. Each should acquire the elements of science, not only of physics and chemistry, but also of biology and anthropology. On the other hand, the predominance of the classical training over modern ought to be restricted. Every student and every faculty should be occupied with only philosophy and science in the first sessions, and not take up special studies until afterwards.

At the close of the Riddle I brought out in clear relief the antagonism between modern monism and traditional dualism, but also pointed out that

this strenuous opposition may be toned down to a certain degree on clear and logical reflection—may, indeed, be converted into a friendly harmony. In a thoroughly logical mind, applying the highest principles with equal force in the entire field of the cosmos—in both organic and inorganic nature—the antithetical positions of theism and pantheism, vitalism and mechanism, approach until they touch each other. Unfortunately, consecutive thought is a rare phenomenon in nature.

This conciliatory disposition has grown stronger and stronger in me. Every year increases my belief that the dualism of Kant and the prevalent metaphysical school must give way to the monism of Goethe and the rising pantheistic tendency. In this we do not lose sight of our ideals. On the contrary, our "realist philosophy of life" teaches us that they are rooted deep in human nature. While occupying ourselves with the ideal world in art and poetry, and cultivating the play of emotion, we persist, nevertheless, in thinking that the real world, the object of science, can be truly known only by experience and pure reason. Truth and poetry are then united in the perfect harmony of monism.

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