CHAPTER XIII

THE EVOLUTION OF THE WORLD

The Notion of Creation--Miracles--Creation of the Whole Universe and of its Various Parts--Creation of Substance (Cosmological Creation)--Deism: One Creative Day--Creation of Separate Entities--Five Forms of Ontological Creationism--Theory of Evolution--I. Monistic Cosmogony--Beginning and End of the World--The Infinity and Eternity of the Universe--Space and Time--_Universum perpetuum mobile_--Entropy of the Universe--II. Monistic Geogeny--History of the Inorganic and Organic Worlds--III. Monistic Biogeny--Transformism and the Theory of Descent: Lamarck and Darwin--IV. Monistic Anthropogeny--Origin of Man

The greatest, vastest, and most difficult of all cosmic problems is that of the origin and development of the world--the "question of creation," in a word. Even to the solution of this most difficult world-riddle the nineteenth century has contributed more than all its predecessors; in a certain sense, indeed, it has found the solution. We have at least attained to a clear view of the fact that all the partial questions of creation are indivisibly connected, that they represent one single, comprehensive "cosmic problem," and that the key to this problem is found in the one magic word--evolution. The great questions of the creation of man, the creation of the animals and plants, the creation of the earth and the sun, etc., are all parts of the general question, What is the origin of the whole world? Has it been _created_ by supernatural power, or has it been _evolved_ by a natural process? What are the causes and the manner of this evolution? If we succeed in finding the correct answer to one of these questions, we have, according to our monistic conception of the world, cast a brilliant light on the solution of them all, and on the entire cosmic problem.

The current opinion as to the origin of the world in earlier ages was almost a universal belief in creation. This belief has been expressed in thousands of interesting, more or less fabulous, legends, poems, cosmogonies, and myths. A few great philosophers were devoid of it, especially those remarkable free-thinkers of classical antiquity who first conceived the idea of natural evolution. All the creation-myths, on the contrary, were of a supernatural, miraculous, and transcendental character. Incompetent, as it was, to investigate for itself the nature of the world and its origin by natural causes, the undeveloped mind naturally had recourse to the idea of miracle. In most of these creation-myths _anthropism_ was blended with the belief in the miraculous. The creator was supposed to have constructed the world on a definite plan, just as man accomplishes his artificial constructions; the conception of the creator was generally completely anthropomorphic, a palpable "anthropistic creationism." The "all-mighty maker of heaven and earth," as he is called in Genesis and the Catechism, is just as humanly conceived as the modern creator of Agassiz and Reinke, or the intelligent "engineer" of other recent biologists.

Entering more fully into the notion of creation, we can distinguish as two entirely different acts the production of the universe as a whole and the partial production of its various parts, in harmony with Spinoza's idea of _substance_ (the universe) and _accidents_ (or _modes_, the individual phenomena of substance). This distinction is of great importance, because there are many eminent philosophers who admit the one and reject the other.

According to this creationist theory, then, God has "made the world out of nothing." It is supposed that God (a rational, but immaterial, being) existed by himself for an eternity before he resolved to create the world. Some supporters of the theory restrict God's creative function to one single act; they believe that this extramundane God (the rest of whose life is shrouded in mystery) created the substance of the world in a single moment, endowed it with the faculty of the most extensive evolution, and troubled no further about it. This view may be found, for instance, in the English Deists in many forms. It approaches very close to our monistic theory of evolution, only abandoning it in the one instant in which God accomplished the creation. Other creationists contend that God did not confine himself to the mere creation of matter, but that he continues to be operative as the "sustainer and ruler of the world." Different modifications of this belief are found, some approaching very close to _pantheism_ and others to complete _theism_. All these and similar forms of belief in creation are incompatible with the law of the persistence of matter and force; that law knows nothing of a beginning.

It is interesting to note that E. du Bois-Reymond has identified himself with this cosmological creationism in his latest speech (on "Neovitalism," 1894). "It is more consonant with the divine omnipotence," he says, "to assume that it created the whole material of the world in one creative act unthinkable ages ago in such wise that it should be endowed with inviolable laws to control the origin and the progress of living things--that, for instance, here on earth rudimentary organisms should arise from which, without further assistance, the whole of living nature could be evolved, from a primitive bacillus to the graceful palm-wood, from a primitive micrococcus to Solomon's lovely wives or to the brain of Newton. Thus we are content with _one_ creative day, and we derive organic nature mechanically, without the aid of either old or new vitalism." Du Bois-Reymond here shows, as in the question of consciousness, the shallow and illogical character of his monistic thought.

According to another still prevalent theory, which may be called "ontological creationism," God not only created the world at large, but also its separate contents. In the Christian world the old Semitic legend of creation, taken from Genesis, is still very widely accepted; even among modern scientists it finds an adherent here and there. I have fully entered into the criticism of it in the first chapter of my _Natural History of Creation_. The following theories may be enumerated as the most interesting modifications of this ontological creationism:

I. _Dualistic creation._--God restricted his interference to _two_ creative acts. First he created the inorganic world, mere dead substance, to which alone the law of energy applies, working blindly and aimlessly in the mechanism of material things and the building of the mountains; then God attained intelligence and communicated it to the purposive intelligent forces which initiate and control organic evolution.[26]

II. _Trialistic creation._--God made the world in _three_ creative acts: (_a_) the creation of the heavens--the extra-terrestrial world, (_b_) the creation of the earth (as the centre of the world) and of its living inhabitants, and (_c_) the creation of man (in the image and likeness of God). This dogma is still widely prevalent among theologians and other "educated" people; it is taught as the truth in many of our schools.

III. _Heptameral creation_; a creation in seven days (_teste_ Moses).--Although few educated people really believe in this Mosaic myth now, it is still firmly impressed on our children in the biblical lessons of their earliest years. The numerous attempts that have been made, especially in England, to harmonize it with the modern theory of evolution have entirely failed. It obtained some importance in science when Linné adopted it in the establishment of his system, and based his definition of organic species (which he considered to be unchangeable) on it: "There are as many different species of animals and plants as there were different forms created in the beginning by the Infinite." This dogma was pretty generally held until the time of Darwin (1859), although Lamarck had already proved its untenability in 1809.

IV. _Periodic creation._--At the beginning of each period of the earth's history the whole population of animals and plants was created anew, and destroyed by a general catastrophe at its close; there were as many general creative acts as there are distinct geological periods (the catastrophic theory of Cuvier [1818] and Louis Agassiz [1858]). Palæontology, which seemed to support this theory in its more imperfect stage, has since completely refuted it.

V. _Individual creation._--Every single man--and every individual animal and plant--does not arise by a natural process of growth, but is created by the favor of God. This view of creation is still often met with in journals, especially in the "births" column. The special talents and features of our children are often gratefully acknowledged to be "gifts of God"; their hereditary defects fit into another theory.

The error of these creation-legends and the cognate belief in miracles must have been apparent to thoughtful minds at an early period; more than two thousand years ago we find that many attempts were made to replace them by a rational theory, and to explain the origin of the world by natural causes. In the front rank, once more, we must place the leaders of the Ionic school, with Democritus, Heraclitus, Empedocles, Aristotle, Lucretius, and other ancient philosophers. The first imperfect attempts which they made astonish us, in a measure, by the flashes of mental light in which they anticipate modern ideas. It must be remembered that classical antiquity had not that solid groundwork for scientific speculation which has been provided by the countless observations and experiments of modern scientists. During the Middle Ages--especially during the domination of the papacy--scientific work in this direction entirely ceased. The torture and the stake of the Inquisition insured that an unconditional belief in the Hebrew mythology should be the final answer to all the questions of creation. Even the phenomena which led directly to the observation of the _facts_ of evolution--the embryology of the plant and the animal, and of man--remained unnoticed, or only excited the interest of an occasional keen observer; but their discoveries were ignored or forgotten. Moreover, the path to a correct knowledge of natural development was barred by the dominant theory of preformation, the dogma which held that the characteristic form and structure of each animal and plant were already sketched in miniature in the germ (cf. p. 54).

The science which we now call the science of evolution (in the broadest sense) is, both in its general outline and in its separate parts, a child of the nineteenth century; it is one of its most momentous and most brilliant achievements. Almost unknown in the preceding century, this theory has now become the sure foundation of our whole world-system. I have treated it exhaustively in my _General Morphology_ (1866), more popularly in my _Natural History of Creation_ (1868), and in its special application to man in my _Anthropogeny_ (1874). Here I shall restrict myself to a brief survey of the chief advances which the science has made in the course of the century. It falls into four sections, according to the nature of its object; that is, it deals with the natural origin of (1) the cosmos, (2) the earth, (3) terrestrial forms of life, and (4) man.

I.--MONISTIC COSMOGONY

The first attempt to explain the constitution and the mechanical origin of the world in a simple manner by "Newtonian laws"--that is, by mathematical and physical laws--was made by Immanuel Kant in the famous work of his youth (1755), _General History of the Earth and Theory of the Heavens_. Unfortunately, this distinguished and daring work remained almost unknown for ninety years; it was only disinterred in 1845 by Alexander Humboldt in the first volume of his _Cosmos_. In the mean time the great French mathematician, Pierre Laplace, had arrived independently at similar views to those of Kant, and he gave them a mathematical foundation in his _Exposition du Système du Monde_ (1796). His chief work, the _Mécanique Céleste_, appeared a hundred years ago. The analogous features of the cosmogony of Kant and Laplace consist, as is well known, in a mechanical explanation of the movements of the planets, and the conclusion which is drawn therefrom, that all the cosmic bodies were formed originally by a condensation of rotating nebulous spheres. This "nebular hypothesis" has been much improved and supplemented since, but it is still the best of all the attempts to explain the origin of the world on monistic and mechanical lines. It has recently been strongly confirmed and enlarged by the theory that this cosmogonic process did not simply take place once, but is periodically repeated. While new cosmic bodies arise and develop out of rotating masses of nebula in some parts of the universe, in other parts old, extinct, frigid suns come into collision, and are once more reduced by the heat generated to the condition of nebulæ.

Nearly all the older and the more recent cosmogonies, including most of those which were inspired by Kant and Laplace, started from the popular idea that the world had had a beginning. Hence, according to a widespread version of the nebular hypothesis, "in the beginning" was made a vast nebula of infinitely attenuated and light material, and at a certain moment ("countless ages ago") a movement of rotation was imparted to this mass. Given this "first beginning" of the cosmogonic movement, it is easy, on mechanical principles, to deduce and mathematically establish the further phenomena of the formation of the cosmic bodies, the separation of the planets, and so forth. This first "origin of movement" is Du Bois-Reymond's second "world-enigma"; he regards it as transcendental. Many other scientists and philosophers are equally helpless before this difficulty; they resign themselves to the notion that we have here a primary "supernatural impetus" to the scheme of things, a "miracle."

In our opinion, this second "world-enigma" is solved by the recognition that movement is as innate and original a property of substance as is sensation. The proof of this monistic assumption is found, first, in the law of substance, and, secondly, in the discoveries which astronomy and physics have made in the latter half of the century. By the spectral analysis of Bunsen and Kirchhoff (1860) we have found, not only that the millions of bodies, which fill the infinity of space, are of the same material as our own sun and earth, but also that they are in various stages of evolution; we have obtained by its aid information as to the movements and distances of the stars, which the telescope would never have given us. Moreover, the telescope itself has been vastly improved, and has, in alliance with photography, made a host of scientific discoveries of which no one dreamed at the beginning of the century. In particular, a closer acquaintance with comets, meteorites, star-clusters, and nebulæ has helped us to realize the great significance of the smaller bodies which are found in millions in the space between the stars.

We now know that the _paths_ of the millions of heavenly bodies are _changeable_, and to some extent irregular, whereas the planetary system was formerly thought to be constant, and the rotating spheres were described as pursuing their orbits in eternal regularity. Astro-physics owes much of its triumph to the immense progress of other branches of physics, of optics, and electricity, and especially of the theory of ether. And here, again, our supreme law of substance is found to be one of the most valuable achievements of modern science. We now know that it rules unconditionally in the most distant reaches of space, just as it does in our planetary system, in the most minute particle of the earth as well as in the smallest cell of our human frame. We are, moreover, justified in concluding, if we are not logically compelled to conclude, that the persistence of matter and force has held good throughout all time as it does to-day. Through all eternity the infinite universe has been, and is, subject to the law of substance.

From this great progress of astronomy and physics, which mutually elucidate and supplement each other, we draw a series of most important conclusions with regard to the constitution and evolution of the cosmos, and the persistence and transformation of substance. Let us put them briefly in the following theses:

I. The _extent_ of the universe is infinite and unbounded; it is empty in no part, but everywhere filled with substance.

II. The _duration_ of the world is equally infinite and unbounded; it has no beginning and no end: it is eternity.

III. Substance is everywhere and always in uninterrupted movement and transformation: nowhere is there perfect repose and rigidity; yet the infinite quantity of matter and of eternally changing force remains constant.

IV. This universal movement of substance in space takes the form of an eternal cycle or of a periodical process of evolution.

V. The phases of this evolution consist in a periodic change of consistency, of which the first outcome is the primary division into mass and ether--the ergonomy of ponderable and imponderable matter.

VI. This division is effected by a progressive condensation of matter as the formation of countless infinitesimal "centres of condensation," in which the inherent primitive properties of substance--feeling and inclination--are the active causes.

VII. While minute and then larger bodies are being formed by this pyknotic process in one part of space, and the intermediate ether increases its strain, the opposite process--the destruction of cosmic bodies by collision--is taking place in another quarter.

VIII. The immense quantity of heat which is generated in this mechanical process of the collision of swiftly moving bodies represents the new kinetic energy which effects the movement of the resultant nebulæ and the construction of new rotating bodies. The eternal drama begins afresh. Even our mother earth, which was formed of part of the gyrating solar system millions of ages ago, will grow cold and lifeless after the lapse of further millions, and, gradually narrowing its orbit, will fall eventually into the sun.

It seems to me that these modern discoveries as to the periodic decay and re-birth of cosmic bodies, which we owe to the most recent advance of physics and astronomy, associated with the law of substance, are especially important in giving us a clear insight into the universal cosmic process of evolution. In their light our earth shrinks into the slender proportions of a "mote in the sunbeam," of which unnumbered millions chase each other through the vast depths of space. Our own "human nature," which exalted itself into an image of God in its anthropistic illusion, sinks to the level of a placental mammal, which has no more value for the universe at large than the ant, the fly of a summer's day, the microscopic infusorium, or the smallest bacillus. Humanity is but a transitory phase of the evolution of an eternal substance, a particular phenomenal form of matter and energy, the true proportion of which we soon perceive when we set it on the background of infinite space and eternal time.

Since Kant explained space and time to be merely "forms of perception"--space the form of external, time of internal, sensitivity--there has been a keen controversy, which still continues, over this important problem. A large section of modern metaphysicians have persuaded themselves that this "critical fact" possesses a great importance as the starting-point of "a purely idealist theory of knowledge," and that, consequently, the natural opinion of the ordinary healthy mind as to the _reality_ of time and space is swept aside. This narrow and ultra-idealist conception of time and space has become a prolific source of error. It overlooks the fact that Kant only touched one side of the problem, the _subjective_ side, in that theory, and recognized the equal validity of its _objective_ side. "Time and space," he said, "have empirical reality, but transcendental ideality." Our modern monism is quite compatible with this thesis of Kant's, but not with the one-sided exaggeration of the subjective aspect of the problem; the latter leads logically to the absurd idealism that culminates in Berkeley's thesis, "Bodies are but ideas; their essence is in their perception." The thesis should be read thus: "Bodies are only ideas for my personal consciousness; their existence is just as real as that of my organs of thought, the ganglionic cells in the gray bed of my brain, which receive the impress of bodies on my sense-organs and form those ideas by association of the impressions." It is just as easy to doubt or to deny the reality of my own consciousness as to doubt that of time and space. In the delirium of fever, in hallucinations, in dreams, and in double-consciousness, I take ideas to be true which are merely fancies. I mistake my own personality for another (_vide_ p. 185); Descartes' famous _Cogito ergo sum_ applies no longer. On the other hand, the reality of time and space is now fully established by that expansion of our philosophy which we owe to the law of substance and to our monistic cosmogony. When we have happily got rid of the untenable idea of "empty space," there remains as the infinite "space-filling"-medium matter, in its two forms of ether and mass. So also we find a "time-filling" event in the eternal movement, or genetic energy, which reveals itself in the uninterrupted evolution of substance, in the _perpetuum mobile_ of the universe.

As a body which has been set in motion continues to move as long as no external agency interferes with it, the idea was conceived long ago of constructing an apparatus which should illustrate perpetual motion. The fact was overlooked that every movement meets with external impediments and gradually ceases, unless a new impetus is given to it from without and a new force is introduced to counteract the impediments. Thus, for instance, a pendulum would swing backward and forward for an eternity at the same speed if the resistance of the atmosphere and the friction at the point it hangs from did not gradually deprive it of the mechanical kinetic energy of its motion and convert it into heat. We have to furnish it with fresh mechanical energy by a spring (or, as in the pendulum-clock, by the drag of a weight). Hence it is impossible to construct a machine that would produce, without external aid, a surplus of energy by which it could keep itself going. Every attempt to make such a _perpetuum mobile_ must necessarily fail; the discovery of the law of substance showed, in addition, the theoretical impossibility of it.

The case is different, however, when we turn to the world at large, the boundless universe that is in eternal movement. The infinite matter, which fills it objectively, is what we call _space_ in our subjective impression of it; _time_ is our subjective conception of its eternal movement, which is, objectively, a periodic, cyclic evolution. These two "forms of perception" teach us the infinity and eternity of the universe. That is, moreover, equal to saying that the universe itself is a _perpetuum mobile_. This infinite and eternal "machine of the universe" sustains itself in eternal and uninterrupted movement, because every impediment is compensated by an "equivalence of energy," and the unlimited sum of kinetic and potential energy remains always the same. The law of the persistence of force proves also that the idea of a _perpetuum mobile_ is just as applicable to, and as significant for, the cosmos as a whole as it is impossible for the isolated action of any part of it. Hence the theory of _entropy_ is likewise untenable.

The able founder of the mechanical theory of heat (1850), Clausius, embodied the momentous contents of this important theory in two theses. The first runs: "The energy of the universe is constant"--that is one-half of our law of substance, the principle of energy (_vide_ p. 230). The second thesis is: "The energy of the universe tends towards a maximum." In my opinion this second assertion is just as erroneous as the first is true. In the theory of Clausius the entire energy of the universe is of two kinds, one of which (heat of the higher degree, mechanical, electrical, chemical energy, etc.) is partly convertible into work, but the other is not; the latter energy, already converted into heat and distributed in the cooler masses, is irrevocably lost as far as any further work is concerned. Clausius calls this unconsumed energy, which is no longer available for mechanical work, _entropy_ (that is, force that is directed _inward_); it is continually increasing at the cost of the other half. As, therefore, the mechanical energy of the universe is daily being transformed into heat, and this cannot be reconverted into mechanical force, the sum of heat and energy in the universe must continually tend to be reduced and dissipated. All difference of temperature must ultimately disappear, and the completely latent heat must be equally distributed through one inert mass of motionless matter. All organic life and movement must cease when this maximum of _entropy_ has been reached. That would be a real "end of the world."

If this theory of entropy were true, we should have a "beginning" corresponding to this assumed "end" of the world--a minimum of entropy, in which the differences in temperature of the various parts of the cosmos would be at a maximum. Both ideas are quite untenable in the light of our monistic and consistent theory of the eternal cosmogenetic process; both contradict the law of substance. There is neither beginning nor end of the world. The universe is infinite, and eternally in motion; the conversion of kinetic into potential energy, and _vicissim_, goes on uninterruptedly; and the sum of this actual and potential energy remains constant. The second thesis of the mechanical theory of heat contradicts the first, and so must be rejected.

The representatives of the theory of entropy are quite correct as long as they confine themselves to distinct processes, in which, _under certain conditions_, the latent heat cannot be reconverted into work. Thus, for instance, in the steam-engine the heat can only be converted into mechanical work when it passes from a warmer body (steam) into a cooler (water); the process cannot be reversed. In the world at large, however, quite other conditions obtain--conditions which permit the reconversion of latent heat into mechanical work. For instance, in the collision of two heavenly bodies, which rush towards each other at inconceivable speed, enormous quantities of heat are liberated, while the pulverized masses are hurled and scattered about space. The eternal drama begins afresh--the rotating mass, the condensation of its parts, the formation of new meteorites, their combination into larger bodies, and so on.

II.--MONISTIC GEOGENY

The history of the earth, of which we are now going to make a brief survey, is only a minute section of the history of the cosmos. Like the latter, it has been the object of philosophic speculation and mythological fantasy for many thousand years. Its true scientific study, however, is much younger; it belongs, for the most part, to the nineteenth century. The fact that the earth is a planet revolving round the sun was determined by the system of Copernicus (1543); Galilei, Kepler, and other great astronomers, mathematically determined its distance from the sun, the laws of its motion, and so forth. Kant and Laplace indicated, in their cosmogony, the way in which the earth had been developed from the parent sun. But the later history of the earth, the formation of its crust, the origin of its seas and continents, its mountains and deserts, was rarely made the subject of serious scientific research in the eighteenth century, and in the first two decades of the nineteenth. As a rule, men were satisfied with unreliable conjectures or with the traditional story of creation; once more the Mosaic legend barred the way to an independent investigation.

In 1822 an important work appeared, which followed the same method in the scientific investigation of the history of the earth that had already proved the most fertile--the _ontological_ method, or the principle of "actualism." It consists in a careful study and manipulation of _actual_ phenomena with a view to the elucidation of the analogous historical processes of the past. The Society of Science at Göttingen had offered a prize in 1818 for "the most searching and comprehensive inquiry into the changes in the earth's crust which are historically demonstrable, and the application which may be made of a knowledge of them in the investigation of the terrestrial revolutions which lie beyond the range of history." This prize was obtained by Karl Hoff, of Gotha, for his distinguished work, _History of the Natural Changes in the Crust of the Earth in the Light of Tradition_ (1822-34). Sir Charles Lyell then applied this _ontological_ or _actualistic_ method with great success to the whole province of geology; his _Principles of Geology_ (1830) laid the firm foundation on which the fabric of the history of the earth was so happily erected. The important geogenetic research of Alexander Humboldt, Leopold Buch, Gustav Bischof, Edward Süss, and other geologists, were wholly based on the empirical foundation and the speculative principles of Karl Hoff and Charles Lyell. They cleared the way for purely rational science in the field of geology; they removed the obstacles that had been put in the path by mythological fancy and religious tradition, especially by the Bible and its legends. I have already discussed the merits of Lyell, and his relations with his friend Charles Darwin, in the sixteenth and seventeenth chapters of my _Natural History of Creation_, and must refer the reader to the standard works on geology for a further acquaintance with the history of the earth and the great progress which dynamical and historical geology have made during the century.

The first division of the history of the earth must be a separation of inorganic and organic geogeny; the latter begins with the first appearance of living things on our planet. The earlier section, the inorganic history of the earth, ran much the same course as that of the other planets of our system. They were all cast off as rings of nebula at the equator of the rotating solar mass, and gradually condensed into independent bodies. After cooling down a little, the glowing ball of the earth was formed out of the gaseous mass, and eventually, as the heat continued to radiate out into space, there was formed at its surface the thin solid crust on which we live. When the temperature at the surface had gone down to a certain point, the water descended upon it from the environing clouds of steam, and thus the first condition was secured for the rise of organic life. Many million years--certainly more than a hundred--have passed since this important process of the formation of water took place, introducing the third section of cosmogony, which we call _biogeny_.

III.--MONISTIC BIOGENY

The third phase of the evolution of the world opens with the advent of organisms on our planet, and continues uninterrupted from that point until the present day. The great problems which this most interesting part of the earth's history suggests to us were still thought insoluble at the beginning of the nineteenth century, or, at least, so difficult that their solution seemed to be extremely remote. Now, at the close of the century, we can affirm with legitimate pride that they have been substantially solved by modern biology and its theory of transformism; indeed, many of the phenomena of the organic world are now interpreted on physical principles as completely as the familiar physical phenomena of inorganic nature. The merit of making the first important step in this difficult path and of pointing out the way to the monistic solution of all the problems of biology must be accorded to the great French scientist, Jean Lamarck; it was in 1809, the year of the birth of Charles Darwin, that he published his famous _Philosophie Zoologique_. In this original work not only is a splendid effort made to interpret all the phenomena of organic life from a monistic and physical point of view, but the path is opened which alone leads to the solution of the greatest enigma of this branch of science--the problem of the natural origin of organic species. Lamarck, who had an equally extensive empirical acquaintance with zoology and botany, drew the first sketch of the theory of descent; he showed that all the countless members of the plant and animal kingdoms have arisen by slow transformation from simple, common ancestral types, and that it is the gradual modification of forms by _adaptation_, in reciprocal action with _heredity_, which has brought about this secular metamorphosis.

I have fully appreciated the merit of Lamarck in the fifth chapter, and of Darwin in the sixth and seventh chapters, of the _Natural History of Creation_. Darwin, fifty years afterwards, not only gave a solid foundation to all the essential parts of the theory of descent, but he filled up the _lacunae_ of Lamarck's work by his theory of selection. Darwin reaped abundantly the success that Lamarck had never seen, with all his merit. His epoch-making work on _The Origin of Species by Natural Selection_ has transformed modern biology from its very foundations, in the course of the last forty years, and has raised it to a stage of development that yields to no other science in existence. Darwin is _the Copernicus of the organic world_, as I said in 1868, and E. du Bois-Reymond repeated fifteen years afterwards.[27]

IV.--MONISTIC ANTHROPOGENY

The fourth and last phase of the world's history must be for us men that latest period of time which has witnessed the development of our own race. Lamarck (1809) had already recognized that this evolution is only rationally conceivable as the outcome of a natural process, by "descent from the apes," our next of kin among the mammals. Huxley then proved, in his famous essay on _The Place of Man in Nature_, that this momentous thesis is an inevitable consequence of the theory of descent, and is thoroughly established by the facts of anatomy, embryology, and palæontology. He considered this "question of all questions" to be substantially answered. Darwin followed with a brilliant discussion of the question under many aspects in his _Descent of Man_ (1871). I had myself devoted a special chapter to this important problem of the science of evolution in my _General Morphology_ (1866). In 1874 I published my _Anthropogeny_, which contains the first attempt to trace the descent of man through the entire chain of his ancestry right up to the earliest archigonous monera; the attempt was based equally on the three great "documents" of evolutionary science--anatomy, embryology, and palæontology. The progress we have made in anthropogenetic research during the last few years is described in the paper which I read on "Our Present Knowledge of the Origin of Man" at the International Congress of Zoologists at Cambridge in 1898.[28]