PIONEERS OF EVOLUTION FROM THALES TO HUXLEY 1

PIONEERS OF EVOLUTION FROM THALES TO HUXLEY 1

PIONEERS OF EVOLUTION FROM THALES TO HUXLEY With an Intermediate Chapter on the Causes of Arrest of the Movement by EDWARD CLODD President of the Folk-Lore Society Author of the Childhood of the World, The Story of Creation, The Story of Primitive Man, etc. With Portraits New York D. Appleton and Company 1897 Copyright, 1897, by D. Appleton and Company.   To MY BELOVED   A. A. L.   WHOSE FELLOWSHIP AND HELP   HAVE SWEETENED LIFE. PREFACE. This book needs only brief introduction. It attempts to tell the story of the origin of the Evolution idea in Ionia, and, after long arrest, of the revival of that idea in modern times, when its profound and permanent influence on thought in all directions, and, therefore, on human relations and conduct, is apparent. Between birth and revival there were the centuries of suspended animation, when the nepenthe of dogma drugged the reason; the Church teaching, and the laity mechanically accepting, the sufficiency of the Scriptures and of the General Councils to decide on matters which lie outside the domain of both. Hence the necessity for particularizing the causes which actively arrested advance in knowledge for sixteen hundred years. In indicating the parts severally played in the Renascence of Evolution by a small group of illustrious men, the writer, through the courtesy of Mr. Herbert Spencer, has been permitted to see the original documents which show that the theory of Evolution as a whole; i. e., as dealing with the non-living, as well as with the living, contents of the Universe, was formulated by Mr. Spencer in the year preceding the publication of the Origin of Species.   ROSEMONT, TUFNELL PARK, LONDON, N.,     _14th December, 1896_. CONTENTS.                         PART I.                                                          PAGE   PIONEERS OF EVOLUTION FROM THALES TO LUCRETIUS--B. C.         600-A. D. 50                                        1                         PART II.   THE ARREST OF INQUIRY--A. D. 50-A. D. 1600.     1. FROM THE EARLY CHRISTIAN PERIOD TO THE TIME         OF AUGUSTINE--A. D. 50-A. D. 400                    37     2. FROM AUGUSTINE TO LORD BACON--A. D. 400-A. D. 1600   73                         PART III.   THE RENASCENCE OF SCIENCE--A. D. 1600 ONWARD              99                         PART IV.   MODERN EVOLUTION--     1. DARWIN AND WALLACE                                  126     2. HERBERT SPENCER                                     175     3. THOMAS HENRY HUXLEY                                 201   INDEX                                                    267   "Nature, which governs the whole, will soon change all things which   thou seest, and out of their substance will make other things, and   again other things from the substance of them, in order that the   world may be ever new."                                      _Marcus Aurelius_, vii, 25. PIONEERS OF EVOLUTION. _PART I._ PIONEERS OF EVOLUTION FROM THALES TO LUCRETIUS. B. C. 600-A. D. 50.   "These all died in faith, not having received the promises, but     having seen them afar off, and were persuaded of them."--HEBREWS     xi. 13. "One event is always the son of another, and we must never forget the parentage," said a Bechuana chief to Casalis the missionary. The barbarian philosopher spoke wiser than he knew, for in his words lay that doctrine of continuity and unity which is the creed of modern science. They are a suitable text to the discourse of this chapter, the design of which is to bring out what the brilliancy of present-day discoveries tends to throw into shadow, namely, the antiquity of the ideas of which those discoveries are the result. Although the Theory of Evolution, as we define it, is new, the speculations which made it possible are, at least, twenty-five centuries old. Indeed, it is not practicable, since the remote past yields no documents, to fix their beginnings. Moreover, charged, as they are, with many crudities, they are not detachable from the barbaric conceptions of the Universe which are the philosophies of past, and the legends of present, times. Fontenelle, a writer of the last century, shrewdly remarked that "all nations made the astounding part of their myths while they were savage, and retained them from custom and religious conservatism." For, as Walter Bagehot argues in his brilliant little book on Physics and Politics, and as all anthropological research goes to prove, the lower races are non-progressive both through fear and instinct. And the majority of the members of higher races have not escaped from the operation of the same causes. Hence the persistence of coarse and grotesque elements in speculations wherein man has made gradual approach to the truth of things; hence, too--the like phenomena having to be interpreted--the similarity of the explanation of them. And as primitive myth embodies primitive theology, primitive morals, and primitive science, the history of beliefs shows how few there be who have escaped from the tyranny of that authority and sanctity with which the lapse of time invests old ideas. Dissatisfaction is a necessary condition of progress; and dissatisfaction involves opposition. As Grant Allen puts it, in one of his most felicitous poems:     If systems that be are the order of God,     Revolt is a part of the order. Hence a stage in the history of certain peoples when, in questioning what is commonly accepted, intellectual freedom is born. Such a stage was markedly reached whenever, for example, an individual here and there challenged the current belief about the beginnings and nature of things, beliefs held because they were taught, not because their correspondence with fact had been examined. A pioneer (French, _pionnier_; Italian, _pedone_; from Latin _pedes_) is, literally, a foot-soldier; one who goes before an army to clear the road of obstructions. Hence the application of the term to men who are in the van of any new movement; hence its special fitness in the present connection, as designating men whose speculations cut a pathway through jungles of myth and legend to the realities of things. The Pioneers of Evolution--the first on record to doubt the truth of the theory of special creation, whether as the work of departmental gods or of one Supreme Deity, matters not--lived in Greece about the time already mentioned; six centuries before Christ. Not in the early stages of the Evolution idea, in the Greece limited, as now, to a rugged peninsula in the southeastern corner of Europe and to the surrounding islands, but in the Greece which then included Ionia, on the opposite seaboard of Asia Minor. From times beyond memory or record, the islands of the Ægean had been the nurseries of culture and adventure. Thence the maritime inhabitants had spread themselves both east and west, feeding the spirit of inquiry, and imbibing influences from older civilizations, notably of Egypt and Chaldæa. But, mix as they might with other peoples, the Greeks never lost their own strongly marked individuality, and, in imparting what they had acquired or discovered to younger peoples, that is, younger in culture, they stamped it with an impress all their own. At the later period with which we are dealing, refugees from the Peloponnesus, who would not submit to the Dorian yoke, had been long settled in Ionia. To what extent they had been influenced by contact with their neighbours is a question which, even were it easy to answer, need not occupy us here. Certain it is that trade and travel had widened their intellectual horizon, and although India lay too remote to touch them closely (if that incurious, dreamy East had touched them, it would have taught them nothing), there was Babylonia with her star-watchers, and Egypt with her land-surveyors. From the one, these Ionians probably gained knowledge of certain periodic movements of some of the heavenly bodies; and from the other, a few rules of mensuration, perchance a little crude science. But this is conjecture. For all the rest that she evolved, and with which she enriched the world, ancient Greece is in debt to none. While the Oriental shrunk from quest after causes, looking, as Professor Butcher aptly remarks in his Aspects of the Greek Genius, on "each fresh gain of earth as so much robbery of heaven," the Greek eagerly sought for the law governing the facts around him. And in Ionia was born the idea foreign to the East, but which has become the starting-point of all subsequent scientific inquiry--the idea that Nature works by fixed laws. Sir Henry Maine said that "except the blind forces of Nature, nothing moves which is not Greek in its origin," and we feel how hard it is to avoid exaggeration when speaking of the heritage bequeathed by Greece as the giver of every fruitful, quickening idea which has developed human faculty on all sides, and enriched every province of life. Amid serious defects of character, as craftiness, avariciousness, and unscrupulousness, the Greeks had the redeeming grace of pursuit after knowledge which naught could baffle (Plato, Republic, vol. iv, p. 435), and that healthy outlook on things which saved them from morbid introspection. There arose among them no Simeon Stylites to mount his profitless pillar; no filth-ingrained fakir to waste life in contemplating the tip of his nose; no schoolman to idly speculate how many angels could dance upon a needle's point; or to debate such fatuous questions as the language which the saints in heaven will speak after the Last Judgment. In his excellent and cautious survey of Early Greek Philosophy, which we mainly follow in this section, Professor Burnet says that the real advance made by the Ionians was through their "leaving off telling tales. They gave up the hopeless task of describing what was when as yet there was nothing, and asked instead what all things really are now." For the early notions of the Greeks about nature, being an inheritance from their barbaric ancestors, were embodied in myths and legends bearing strong resemblance to those found among the uncivilized tribes of Polynesia and elsewhere in our day. For example, the old nature-myth of Cronus separating heaven and earth by the mutilation of Uranus occurs among Chinese, Japanese, and Maoris, and among the ancient Hindus and Egyptians. The earliest school of scientific speculation was at Miletus, the most flourishing city of Ionia. Thales, whose name heads the list of the "Seven Sages," was its founder. As with other noted philosophers of this and later periods, neither the exact date of his birth nor of his death are known, but the sixth century before Christ may be held to cover the period when he "flourished." That "nothing comes into being out of nothing, and that nothing passes away into nothing," was the conviction with which he and those who followed him started on their quest. All around was change; everything always becoming something else; "all in motion like streams." There must be that which is the vehicle of all the changes, and of all the motions which produce them. _What_, therefore, was this permanent and primary substance? in other words, of what is the world made? And Thales, perhaps through observing that it could become vaporous, liquid, and solid in turn; perhaps--if, as tradition records, he visited Egypt--through watching the wonder-working, life-giving Nile; perhaps as doubtless sharing the current belief in an ocean-washed earth, said that the primary substance was WATER. Anaximander, his friend and pupil, disagreeing with what seemed to him a too concrete answer, argued, in more abstract fashion, that "the material cause and first element of things was the Infinite." This material cause, which he was the first thus to name, "is neither water nor any other of what are now called the _elements_" (we quote from Theophrastus, the famous pupil of Aristotle, born at Eresus in Lesbos, 371 B. C.). Perhaps, following Professor Burnet's able guidance through the complexities of definitions, the term BOUNDLESS best expresses the "one eternal, indestructible substance out of which everything arises, and into which everything once more returns"; in other words, the exhaustless stock of matter from which the waste of existence is being continually made good. Anaximander was the first to assert the origin of life from the non-living, i. e., "the moist element as it was evaporated by the sun," and to speak of man as "like another animal, namely, a fish, in the beginning." This looks well-nigh akin to prevision of the mutability of species, and of what modern biology has proved concerning the marine ancestry of the highest animals, although it is one of many ancient speculations as to the origin of life in slimy matter. And when Anaximander adds that "while other animals quickly find food for themselves, man alone requires a prolonged period of suckling," he anticipates the modern explanation of the origin of the rudimentary family through the development of the social instincts and affections. The lengthening of the period of infancy involves dependence on the parents, and evolves the sympathy which lies at the base of social relations. (Cf. Fiske's Outlines of Cosmic Philosophy, vol. ii, pp. 344, 360.) In dealing with speculations so remote, we have to guard against reading modern meanings into writings produced in ages whose limitations of knowledge were serious, and whose temper and standpoint are wholly alien to our own. For example, shrewd as are some of the guesses made by Anaximander, we find him describing the sun as "a ring twenty-eight times the size of the earth, like a cartwheel with the felloe hollow and full of fire, showing the fire at a certain point, as if through the nozzle of a pair of bellows." And if he made some approach to truer ideas of the earth's shape as "convex and round," the world of his day, as in the days of Homer, thought of it as flat and as floating on the all-surrounding water. The Ionian philosophers lacked not insight, but the scientific method of starting with working hypotheses, or of observation before theory, was as yet unborn. In this brief survey of the subject there will be no advantage in detailing the various speculations which followed on the heels of those of Thales and Anaximander, since these varied only in non-essentials; or, like that of Pythagoras and his school, which Zeller regards as the outcome of the teachings of Anaximander, were purely abstract and fanciful. As is well known, the Pythagoreans, whose philosophy was ethical as well as cosmical, held that all things are made of numbers, each of which they believed had its special character and property. A belief in such symbols as entities seems impossible to us, but its existence in early thought is conceivable when, as Aristotle says, they were "not separated from the objects of sense." Even in the present day, among the eccentric people who still believe in the modern sham agnosticism, known as theosophy, and in astrology, we find the delusion that numbers possess inherent magic or mystic virtues. So far as the ancients are concerned, "consider," as Mr. Benn remarks in his Greek Philosophers (vol. i, p. 12), "the lively emotions excited at a time when multiplication and division, squaring and cubing, the rule of three, the construction and equivalence of figures, with all their manifold applications to industry, commerce, fine arts, and tactics, were just as strange and wonderful as electrical phenomena are to us ... and we shall cease to wonder that a mere form of thought, a lifeless abstraction, should once have been regarded as the solution of every problem; the cause of all existence; or that these speculations were more than once revived in after ages." Xenophanes of Colophon, one of the twelve Ionian cities of Asia Minor, deserves, however, a passing reference. He, with Parmenides and Zeno, are the chief representatives of the Eleatic school, so named from the city in southwestern Italy where a Greek colony had settled. The tendency of that school was toward metaphysical theories. He was the first known observer to detect the value of fossils as evidences of the action of water, but his chief claim to notice rests on the fact that, passing beyond the purely physical speculations of the Ionian school, he denied the idea of a primary substance, and theorized about the nature and actions of superhuman beings. Living at a time when there was a revival of old and gross superstitions to which the vulgar had recourse when fears of invasions arose, he dared to attack the old and persistent ideas about the gods, as in the following sentences from the fragments of his writings: "Homer and Hesiod have ascribed to the gods all things that are a shame and a disgrace among men, theft and adulteries and deception of one another." "There never was nor will be a man who has clear certainty as to what I say about the gods and about all things; for even if he does chance to say what is right, yet he himself does not know that it is so. But all are free to guess." "Mortals think that the gods were born as they are, and have senses and a voice and body like their own. So the Ethiopians make their gods black and snub-nosed; the Thracians give theirs red hair and blue eyes." "There is one god, the greatest among gods and men, unlike mortals both in mind and body." Had such heresies been spoken in Athens, where the effects of a religious revival were still in force, the "secular arm" of the archons would probably have made short work of Xenophanes. But in Elea, or in whatever other colony he may have lived, "the gods were left to take care of themselves." Greater than the philosophers yet named is Heraclitus of Ephesus, nicknamed "the dark," from the obscurity of his style. His original writings have shared the fate of most documents of antiquity, and exist, like many of these, only in fragments preserved in the works of other authors. Many of his aphorisms are indeed dark sayings, but those that yield their meaning are full of truth and suggestiveness. As for example: "The eyes are more exact witnesses than the ears." "You will not find out the boundaries of soul by travelling in any direction." "Man is kindled and put out like a light in the nighttime." "Man's character is his fate." But these have special value as keys to his philosophy: "You cannot step twice into the same rivers; for fresh waters are ever flowing in upon you." "Homer was wrong in saying: 'Would that strife might perish from among gods and men!' He did not see that he was praying for the destruction of the universe; for, if his prayer were heard, all things would pass away." Flux or movement, says Heraclitus, is the all-pervading law of things, and in the opposition of forces, by which things are kept going, there is underlying harmony. Still on the quest after the primary substance whose manifestations are so various, he found it in FIRE, since "the quantity of it in a flame burning steadily appears to remain the same; the flames seems to be what we call a 'thing.' And yet the substance of it is continually changing. It is always passing away in smoke, and its place is always being taken by fresh matter from the fuel that feeds it. This is just what we want. If we regard the world as an 'ever-living fire'--'this order, which is the same in all things, and which no one of gods or men has made'--we can understand how fire is always becoming all things, while all things are always returning to it." And as is the world, so is man, made up, like it, both soul and body, of the fire, the water, and the earth. We are and are not the same for two consecutive moments; "the fire in us is perpetually becoming water, and the water earth, but as the opposite process goes on simultaneously we appear to remain the same." As speculation advanced, it became more and more applied to details, theories of the beginnings of life being followed by theories of the origin of its various forms. This is a feature of the philosophy of Empedocles, who flourished in the fifth century B. C. The advance of Persia westward had led to migrations of Greeks to the south of Italy and Sicily, and it was at Agrigentum, in that island, that Empedocles was born about 490. He has an honoured place among the earliest who supplanted _guesses_ about the world by _inquiry_ into the world itself. Many legends are told of his magic arts, one of which, it will be remembered, Matthew Arnold makes an occasion of some fine reflections in his poem Empedocles in Etna. The philosopher was said to have brought back to life a woman who apparently had been dead for thirty days. As he ascends the mountain, Pausanias of Gela, with an address to whom the poem of Empedocles opens, would fain have his curiosity slaked as to this and other marvels reported of him:     Ask not the latest news of the last miracle,     Ask not what days and nights     In trance Pantheia lay,     But ask how thou such sights     May'st see without dismay;     Ask what most helps when known, thou son of Anchitus. His speculations about things, like those of Parmenides before him and of Lucretius after him, are set down in verse. From the remains of his Poem on Nature we learn that he conceived "the four roots of all things" to be FIRE, AIR, EARTH, and WATER. They are "fools, lacking far-reaching thoughts, who deem that what before was not comes into being, or that aught can perish and be utterly destroyed." Therefore the "roots" or elements are eternal and indestructible. They are acted upon by two forces, which are also material, LOVE and STRIFE; the one a uniting agent, the other a disrupting agent. From the four roots, thus operated upon, arise "the colours and forms" of living things; trees first, both male and female, then fragmentary parts of animals, heads without necks, and "eyes that strayed up and down in want of a forehead," which, combined together, produced monstrous forms. These, lacking power to propagate, perished, and were replaced by "whole-natured" but sexless "forms" which "arose from the earth," and which, as Strife gained the upper hand, became male and female. Herein, amidst much fantastic speculation, would appear to be the germ of the modern theory that the unadapted become extinct, and that only the adapted survive. Nature kills off her failures to make room for her successes. Anaxagoras, who was a contemporary of Empedocles, interests us because he was the first philosopher to repair to Athens, and the first sufferer for truth's sake of whom we have record in Greek annals. Because he taught that the sun was a red-hot stone, and that the moon had plains and ravines in it, he was put upon his trial, and but for the influence of his friend, the famous Pericles, might have suffered death. Speculations, however bold they be, pass unheeded till they collide with the popular creed, and in thus attacking the gods, attack a seemingly divinely settled order. Athens then, and long after, while indifferent about natural science, was, under the influence of the revival referred to above, actively hostile to free thinking. The opinions of Anaxagoras struck at the existence of the gods and emptied Olympus. If the sky was but an air-filled space, what became of Zeus? if the sun was only a fiery ball, what became of Apollo? Mr. Grote says (History of Greece, vol. i, p. 466) that "in the view of the early Greek, the description of the sun, as given in a modern astronomical treatise, would have appeared not merely absurd, but repulsive and impious; even in later times, Anaxagoras and other astronomers incurred the charge of blasphemy for dispersonifying Hēlios." Of Socrates, who was himself condemned to death for impiety in denying old gods and introducing new ones, the same authority writes: "Physics and astronomy, in his opinion, belonged to the divine class of phenomena, in which human research was insane, fruitless, and impious." So Demos and his "betters" clung, as the majority still cling, to the myths of their forefathers. They repaired to the oracles, and watched for the will of the gods in signs and omens. In his philosophy Anaxagoras held that there was a portion of everything in everything, and that things are variously mixed in infinite numbers of seeds, each after its kind. From these, through the action of an external cause, called NOUS, which also is material, although the "thinnest of all things and the purest," and "has power over all things," there arose plants and animals. It is probable, as Professor Burnet remarks, "that Anaxagoras substituted NOUS, still conceived as a body, for the LOVE and STRIFE of Empedocles simply because he wished to retain the old Ionic doctrine of a substance that 'knows' all things, and to identify this with the new theory of a substance that 'moves' all things." Thus far speculation has run largely on the origin of life forms, but now we find revival of speculation about the nature of things generally, and the formulation of a theory which links Greek cosmology with early nineteenth-century science with Dalton's ATOMIC THEORY. Democritus of Abdera, who was born about 460 B. C., has the credit of having elaborated an atomic theory, but probably he only further developed what Leucippus had taught before him. Of this last-named philosopher nothing whatever is known; indeed, his existence has been doubted, but it counts for something that Aristotle gives him the credit of the discovery, and that Theophrastus, in the first book of his Opinions, wrote of Leucippus as follows: "He assumed innumerable and ever-moving elements, namely, the atoms. And he made their forms infinite in number, since there was no reason why they should be of one kind rather than another, and because he saw that there was unceasing becoming and change in things. He held, further, that _what is_ is no more real than _what is not_, and that both are alike causes of the things that come into being; for he laid down that the substance of the atoms was compact and full, and he called them _what is_, while they moved in the void which he called _what is not_, but affirmed to be just as real as _what is_." Thus did "he answer the question that Thales had been the first to ask." Postponing further reference to this theory until the great name of Lucretius, its Roman exponent, is reached, we find a genuine scientific method making its first start in the person of Aristotle. This remarkable man, the founder of the experimental school, and the Father of Natural History, was born 384 B. C. at Stagira in Macedonia. In his eighteenth year he left his native place for Athens, where he became a pupil of Plato. Disappointed, as it is thought, at not succeeding his master in the Academy, he removed to Mytilene in the island of Lesbos, where he received an invitation from Philip of Macedon to become tutor to his son, the famous Alexander the Great. When Alexander went on his expedition to Asia, Aristotle returned to Athens, teaching in the "school" which his genius raised to the first rank. There he wrote the greater part of his works, the completion of some of which was stopped by his death at Chalcis in 322. The range of his studies was boundless, but in this brief notice we must limit our survey--and the more so because Aristotle's speculations outside natural history abound in errors--to his pioneer work in organic evolution. Here, in the one possible method of reaching the truth, theory follows observation. Stagira lay on the Strymonic gulf, and a boyhood spent by the seashore gave Aristotle ample opportunity for noting the variations, and withal gradations, between marine plants and animals, among which last-named it should be noted as proof of his insight that he was keen enough to include sponges. Here was laid the foundation of a classification of life-forms on which all corresponding attempts were based. Then, he saw, as none other before him had seen, and as none after him saw for centuries, the force of heredity, that still unsolved problem of biology. Speaking broadly of his teaching, the details of which would fill pages, its main features are (1) His insistence on observation. In his History of Animals he says "we must not accept a general principle from logic only, but must prove its application to each fact. For it is in facts that we must seek general principles, and these must always accord with facts. Experience furnishes the particular facts from which induction is the pathway to general laws." (2) His rejection of chance and assertion of law, not, following a common error, of law personified as cause, but as the term by which we express the fact that certain phenomena always occur in a certain order. In his Physics Aristotle says that "Jupiter rains not that corn may be increased, but from necessity. Similarly, if some one's corn is destroyed by rain, it does not rain for this purpose, but as an accidental circumstance. It does not appear to be from fortune or chance that it frequently rains in winter, but from necessity." (3) On the question of the origin of life-forms he was nearest of all to its modern solution, setting forth the necessity "that germs should have been first produced, and not immediately animals; and that soft mass which first subsisted was the germ. In plants, also, there is purpose, but it is less distinct; and this shows that plants were produced in the same manner as animals, not by chance, as by the union of olives with grape vines. Similarly, it may be argued, that there should be an accidental generation of the germs of things, but he who asserts this subverts Nature herself, for Nature produces those things which, being continually moved by a certain principle contained in themselves, arrive at a certain end." In the eagerness of theologians to discover proof of a belief in one God among the old philosophers, the references made by Aristotle to a "perfecting principle," an "efficient cause," a "prime mover," and so forth, have been too readily construed as denoting a monotheistic creed which, reminding us of the "one god" of Xenophanes, is also akin to the Personal God of Christianity. "The Stagirite," as Mr. Benn remarks (Greek Philosophers, vol. i, p. 312), "agrees with Catholic theism, and he agrees with the First Article of the English Church, though not with the Pentateuch, in saying that God is without parts or passions, but there his agreement ceases. Excluding such a thing as divine interference with all Nature, his theology, of course, excludes the possibility of revelation, inspiration, miracles, and grace." He is a being who does not interest himself in human affairs. But, differ as the commentators may as to Aristotle's meaning, his assumed place in the orthodox line led, as will be seen hereafter, to the acceptance of his philosophy by Augustine, Bishop of Hippo, in the fourth century, and by other Fathers of the Church, so that the mediæval theories of the Bible, blended with Aristotle, represent the sum of knowledge held as sufficient until the discoveries of Copernicus in the sixteenth century upset the Ptolemaic theory with its fixed earth and system of cycles and epicycles in which the heavenly bodies moved. He thereby upset very much besides. Like Anaximander and others, Aristotle believed in spontaneous generation, although only in the case of certain animals, as of eels from the mud of ponds, and of insects from putrid matter. However, in this, both Augustine and Thomas Aquinas, and many men of science down to the latter part of the seventeenth century, followed him. For example, Van Helmont, an experimental chemist of that period, gave a recipe for making fleas; and another scholar showed himself on a level with the unlettered rustics of to-day, who believe that eels are produced from horse hairs thrown into a pond. Of deeper interest, as marking Aristotle's prevision, is his anticipation of what is known as Epigenesis, or the theory of the development of the germ into the adult form among the higher individuals through the union of the fertilizing powers of the male and female organs. This theory, which was proved by the researches of Harvey, the discoverer of the circulation of the blood, and is accepted by all biologists to-day, was opposed by Malpighi, an Italian physician, born in 1628, the year in which Harvey published his great discovery, and by other prominent men of science down to the last century. Malpighi and his school contended that the perfect animal is already "preformed" in the germ; for example, the hen's egg, before fecundation, containing an excessively minute, but complete, chick. It therefore followed that in any germ the germs of all subsequent offspring must be contained, and in the application of this "box-within-box" theory its defenders even computed the number of human germs concentrated in the ovary of mother Eve, estimating these at two hundred thousand millions! When the "preformation" theory was revived by Bonnet and others in the eighteenth century, Erasmus Darwin, grandfather of Charles Darwin, passed the following shrewd criticism on it: "Many ingenious philosophers have found so great difficulty in conceiving the manner of reproduction in animals that they have supposed all the numerous progeny to have existed in miniature in the animal originally created. This idea, besides its being unsupported by any analogy we are acquainted with, ascribes a greater continuity to organized matter than we can readily admit. These embryons ... must possess a greater degree of minuteness than that which was ascribed to the devils who tempted St. Anthony, of whom twenty thousand were said to have been able to dance a saraband on the point of a needle without the least incommoding each other." Although no theistic element could be extracted by the theologians of the early Christian Church from the systems of Empedocles and Democritus, thereby securing them a share in the influence exercised by the great Stagirite, they were formative powers in Greek philosophy, and, moreover, have "come by their own" in these latter days. Their chief representative in what is known as the Post-Aristotelian period is Epicurus, who was born at Samos, 342 B. C. As with Zeno, the founder of the Stoic school, his teaching has been perverted, so that his name has become loosely identified with indulgence in gross and sensual living. He saw in pleasure the highest happiness, and therefore advocated the pursuit of pleasure to attain happiness, but he did not thereby mean the pursuit of the unworthy. Rather did he counsel the following after pure, high, and noble aims, whereby alone a man could have peace of mind. It is not hard to see that in the minds of men of low ideals the tendency towards passivity which lurked in such teaching would aid their sliding into the pursuit of mere animal enjoyment; hence the gross and limited association of the term Epicurean. Epicurus accepted the theory of Leucippus, and applied it all round. The _faineant_ gods, who dwell serenely indifferent to human affairs, and about whom men should therefore have no dread; all things, whether dead or living, even the ideas that enter the mind; are alike composed of atoms. He also accepted the theory broached by Empedocles as to the survival of fit and capable forms after life had arrived at these through the processes of spontaneous generation and the production of monstrosities. Adopting the physical speculations of these forerunners, he made them the vehicle of didactic and ethical philosophies which inspired the production of the wonderful poem of Lucretius. Between this great Roman and Epicurus--a period of some two centuries--there is no name of sufficient prominence to warrant attention. The decline of Greece had culminated in her conquest by the semi-barbarian Mummius, and in her consequent addition to the provinces of the Roman Empire. What life lingered in her philosophy within her own borders expired with the loss of freedom, and the work done by the Pioneers of Evolution in Greece was to be resumed elsewhere. In the few years of the pre-Christian period that remained the teaching of Empedocles, and of Epicurus as the mouthpiece of the atomic theory, was revived by Lucretius in his De Rerum Natura. Of that remarkable man but little is recorded, and the record is untrustworthy. He was probably born 99 B. C., and died--by his own hand, Jerome says, but of this there is no proof--in his forty-fourth year. It is difficult, taking up his wonderful poem, to resist the temptation to make copious extracts from it, since, even through the vehicle of Mr. Munro's exquisite translation, it is probably little known to the general reader in these evil days of snippety literature. But the temptation must be resisted, save in moderate degree. With the dignity which his high mission inspires, Lucretius appeals to us in the threefold character of teacher, reformer, and poet. "First, by reason of the greatness of my argument, and because I set the mind free from the close-drawn bonds of superstition; and next because, on so dark a theme, I compose such lucid verse, touching every point with the grace of poesy." As a teacher he expounds the doctrines of Epicurus concerning life and nature; as a reformer he attacks superstition; as a poet he informs both the atomic philosophy and its moral application with harmonious and beautiful verse swayed by a fervour that is akin to religious emotion. Discussing at the outset various theories of origins, and dismissing these, notably that which asserts that things came from nothing--"for if so, any kind might be born of anything, nothing would require seed," Lucretius proceeds to expound the teaching of Leucippus and other atomists as to the constitution of things by particles of matter ruled in their movements by unvarying laws. This theory he works all round, explaining the processes by which the atoms unite to carry on the birth, growth, and decay of things, the variety of which is due to variety of form of the atoms and to differences in modes of their combination; the combinations being determined by the affinities or properties of the atoms themselves, "since it is absolutely decreed what each thing can and what it cannot do by the conditions of Nature." Change is the law of the universe; what is, will perish, but only to reappear in another form. Death is "the only immortal"; and it is that and what may follow it which are the chief tormentors of men. "This terror of the soul, therefore, and this darkness, must be dispelled, not by the rays of the sun or the bright shafts of day, but by the outward aspect and harmonious plan of Nature." Lucretius explains that the soul, which he places in the centre of the breast, is also formed of very minute atoms of heat, wind, calm air, and a finer essence, the proportions of which determine the character of both men and animals. It dies with the body, in support of which statement Lucretius advances seventeen arguments, so determined is he to "deliver those who through fear of death are all their lifetime subject to bondage." These themes fill the first three books. In the fourth he grapples with the mental problems of sensation and conception, and explains the origin of belief in immortality as due to ghosts and apparitions which appear in dreams. "When sleep has prostrated the body, for no other reason does the mind's intelligence wake, except because the very same images provoke our minds which provoke them when we are awake, and to such a degree that we seem without a doubt to perceive him whom life has left, and death and earth gotten hold of. This Nature constrains to come to pass because all the senses of the body are then hampered and at rest throughout the limbs, and cannot refute the unreal by real things." In the fifth book Lucretius deals with origins--of the sun, the moon, the earth (which he held to be flat, denying the existence of the antipodes); of life and its development; and of civilization. In all this he excludes design, explaining everything as produced and maintained by natural agents, "the masses, suddenly brought together, became the rudiments of earth, sea, and heaven, and the race of living things." He believed in the successive appearance of plants and animals, but in their arising separately and directly out of the earth, "under the influence of rain and the heat of the sun," thus repeating the old speculations of the emergence of life from slime, "wherefore the earth with good title has gotten and keeps the name of mother." He did not adopt Empedocles's theory of the "four roots of all things," and he will have none of the monsters--the hippogriffs, chimeras, and centaurs--which form a part of the scheme of that philosopher. These, he says, "have never existed," thus showing himself far in advance of ages when unicorns, dragons, and such-like fabled beasts were seriously believed to exist. In one respect, more discerning than Aristotle, he accepts the doctrine of the survival of the fittest as taught by the sage of Agrigentum. For he argues that since upon "the increase of some Nature set a ban, so that they could not reach the coveted flower of age, nor find food, nor be united in marriage," ... "many races of living things have died out, and been unable to beget and continue their breed." Lucretius speaks of Empedocles in terms scarcely less exaggerated than those which he applied to Epicurus. The latter is "a god" "who first found out that plan of life which is now termed wisdom, and who by tried skill rescued life from such great billows and such thick darkness and moored it in so perfect a calm and in so brilliant a light, ... he cleared men's breasts with truth-telling precepts, and fixed a limit to lust and fear, and explained what was the chief good which we all strive to reach." As to Empedocles, "that great country (Sicily) seems to have held within it nothing more glorious than this man, nothing more holy, marvellous, and dear. The verses, too, of this godlike genius cry with a loud voice, and make known his great discoveries, so that he seems scarcely born of a mortal stock." Continuing his speculations on the development of living things, Lucretius strikes out in bolder and original vein. The past history of man, he says, lies in no heroic or golden age, but in one of struggle out of savagery. Only when "children, by their coaxing ways, easily broke down the proud temper of their fathers," did there arise the family ties out of which the wider social bond has grown, and softening and civilizing agencies begin their fair offices. In his battle for food and shelter, "man's first arms were hands, nails and teeth and stones and boughs broken off from the forests, and flame and fire, as soon as they had become known. Afterward the force of iron and copper was discovered, and the use of copper was known before that of iron, as its nature is easier to work, and it is found in greater quantity. With copper they would labour the soil of the earth and stir up the billows of war.... Then by slow steps the sword of iron gained ground and the make of the copper sickle became a byword, and with iron they began to plough through the earth's soil, and the struggles of wavering man were rendered equal." As to language, "Nature impelled them to utter the various sounds of the tongue, and use struck out the names of things." Thus does Lucretius point the road along which physical and mental evolution have since travelled, and make the whole story subordinate to the high purpose of his poem in deliverance of the beings whose career he thus traces from superstition. Man "seeing the system of heaven and the different seasons of the years could not find out by what causes this was done, and sought refuge in handing over all things to the gods and supposing all things to be guided by their nod." Then, in the sixth and last book, the completion of which would seem to have been arrested by his death, Lucretius explains the "law of winds and storms," of earthquakes and volcanic outbursts, which men "foolishly lay to the charge of the gods," who thereby make known their anger.           So, loath to suffer mute,           We, peopling the void air,           Make Gods to whom to impute           The ills we ought to bear;     With God and Fate to rail at, suffering easily.