This paper presents Chapter II, Section 4 from the book THE STORY OF PHILOSOPHY by WILL DURANT. The contents are from the 1933 reprint of this book by TIME INCORPORATED by arrangement with Simon and Schuster, Inc.
The paragraphs of the original material (in black) are accompanied by brief comments (in color) based on the present understanding. Feedback on these comments is appreciated.
The heading below is linked to the original materials.
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IV. The Organization of Science
1. Greek Science Before Aristotle
“Socrates,” says Renan, “gave philosophy to mankind, and Aristotle gave it science. There was philosophy before Socrates, and science before Aristotle; and since Socrates and since Aristotle, philosophy and science have made immense advances. But all has been built upon the foundation which they laid.” Before Aristotle, science was in embryo; with him it was born.
Earlier civilizations than the Greek had made attempts at science; but so far as we can catch their thought through their still obscure cuneiform and hieroglyphic script, their science was indistinguishable from theology. That is to say, these pre-Hellenic peoples explained every obscure operation in nature by some supernatural agency; everywhere there were gods. Apparently it was the Ionian Greeks who first dared to give natural explanations of cosmic complexities and mysterious events: they sought in physics the natural causes of particular incidents, and in philosophy a natural theory of the whole. Thales (640-550 B. C.), the “Father of Philosophy,” was primarily an astronomer, who astonished the natives of Miletus by informing them that the sun and stars (which they were wont to worship as gods) were merely balls of fire. His pupil Anaximander (610-540 B. C.), the first Greek to make astronomical and geographical charts, believed that the universe had begun as an undifferentiated mass, from which all things had arisen by the separation of opposites; that astronomic history periodically repeated itself in the evolution and dissolution of an infinite number of worlds; that the earth was at rest in space by a balance of internal impulsions (like Buridan’s ass); that all our planets had once been fluid, but had been evaporated by the sun; that life had first been formed in the sea, but had been driven upon the land by the subsidence of the water; that of these stranded animals some had developed the capacity to breathe air, and had so become the progenitors of all later land life; that man could not from the beginning have been what he now was, for if man, on his first appearance, had been so helpless at birth, and had required so long an adolescence, as in these later days, he could not possibly have survived. Anaximenes, another Milesian (fl. 450 B. C.), described the primeval condition of things as a very rarefied mass, gradually condensing into wind, cloud, water, earth, and stone; the three forms of matter—gas, liquid and solid—were progressive stages of condensation; heat and cold were merely rarefaction and condensation; earth-quakes were due to the solidification of an originally fluid earth; life and soul were one, an animating and expansive force present in everything everywhere. Anaxagoras (500-428 B. C.), teacher of Pericles, seems to have given a correct explanation of solar and lunar eclipses; he discovered the processes of respiration in plants and fishes; and he explained man’s intelligence by the power of manipulation that came when the fore-limbs were freed from the tasks of locomotion. Slowly, in these men, knowledge grew into science.
First scientific advance was from supernatural agency to natural explanations. The first area of investigation was the heavens and then earth, matter and life; and, ultimately, the investigation of man.
Heraclitus (530-470 B. C.), who left wealth and its cares to live a life of poverty and study in the shade of the temple porticoes at Ephesus, turned science from astronomy to earthlier concerns. All things forever flow and change, he said; even in the stillest matter there is unseen flux and movement. Cosmic history runs in repetitious cycles, each beginning and ending in fire (here is one source of the Stoic and Christian doctrine of last judgment and hell). “Through strife,” says Heraclitus, “all things arise and pass away… War is the father and king of all: some he has made gods, and some men; some slaves, and some free.” Where there is no strife there is decay: “the mixture which is not shaken decomposes.” In this flux of change and struggle and selection, only one thing is constant, and that is law. “This order, the same for all things, no one of gods or men has made; but it always was, and is, and shall be.” Empedocles (fl. 445 B. C., in Sicily) developed to a further stage the idea of evolution. Organs arise not by design but by selection. Nature makes many trials and experiments with organisms, combining organs variously; where the combination meets environmental needs the organism survives and perpetuates its like; where the combination fails, the organism is weeded out; as time goes on, organisms are more and more intricately and successfully adapted to their surroundings. Finally, in Leucippus (fl. 445 B. C.) and Democritus (460-360), master and pupil in Thracian Abdera, we get the last stage of pre-Aristotelian science—materialistic, deterministic atomism. “Everything,” said Leucippus, “is driven by necessity.” “In reality,” said Democritus, “there are only atoms and the void.” Perception is due to the expulsion of atoms from the object upon the sense organ There is or have been or will be an infinite number of worlds, at every moment planets are colliding and dying, and new worlds are rising out of chaos by the selective aggregation of atoms of similar size and shape. There is no design; the universe is a machine.
Then there was speculation on the nature of the universe and its evolution.
This, in dizzy and superficial summary, is the story of Greek science before Aristotle. Its cruder items can be well forgiven when we consider the narrow circle of experimental and observational equipment within which these pioneers were compelled to work. The stagnation of Greek industry under the incubus of slavery prevented the full development of these magnificent beginnings; and the rapid complication of political life in Athens turned the Sophists and Socrates and Plato away from physical and biological research into the paths of ethical and political theory. It is one of the many glories of Aristotle that he was broad and brave enough to compass and combine these two lines of Greek thought, the physical and the moral; that going back beyond his teacher, he caught again the thread of scientific development in the pre- Socratic Greeks, carried on their work with more resolute detail and more varied observation, and brought together all the accumulated results in a magnificent body of organized science.
Earlier scientific investigation lacked the support of experimental and observational equipment.
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2. Aristotle as a Naturalist
If we begin here chronologically, with his Physics, we shall be disappointed; for we find that this treatise is really a metaphysics, an abstruse analysis of matter, motion, space, time, infinity, cause, and other such “ultimate concepts.” One of the more lively passages is an attack on Democritus’ “void”: there can be no void or vacuum in nature, says Aristotle, for in a vacuum all bodies would fall with equal velocity; this being impossible, “the supposed void turns out to have nothing in it”—an instance at once of Aristotle’s very occasional humor, his addiction to unproved assumptions, and his tendency to disparage his predecessors in philosophy. It was the habit of our philosopher to preface his works with historical sketches of previous contributions to the subject in hand, and to add to every contribution an annihilating refutation. “Aristotle, after the Ottoman manner,” says Bacon, “thought he could not reign secure without putting all his brethren to death.” But to this fratricidal mania we owe much of our knowledge of pre-Socratic thought.
Aristotle did not deal much with physics because of the lack of experimental and observational equipment. Before starting his own research in an area, he studied his predecessors and formed his own postulates. He then built up on those postulates.
For reasons already given, Aristotle’s astronomy represents very little advance upon his predecessors. He rejects the view of Pythagoras that the sun is the center of our system; he prefers to give that honor to the earth. But the little treatise on meteorology is full of brilliant observations, and even its speculations strike illuminating fire. This is a cyclic world, says our philosopher: the sun forever evaporates the sea, dries up rivers and springs, and transforms at last the boundless ocean into the barest rock; while conversely the uplifted moisture, gathered into clouds, falls and renews the rivers and the seas. Everywhere change goes on, imperceptibly but effectively. Egypt is “the work of the Nile,” the product of its deposits through a thousand centuries. Here the sea encroaches upon the land, there the land reaches out timidly into the sea; new continents and new oceans rise, old oceans and old continents disappear, and all the face of the world is changed and re-changed in a great systole and diastole of growth and dissolution. Sometimes these vast effects occur suddenly, and destroy the geological and material bases of civilization and even of life; great catastrophes have periodically denuded the earth and reduced man again to his first beginnings; like Sisyphus, civilization has repeatedly neared its zenith only to fall back into barbarism and begIn da capo its upward travail. Hence the almost “eternal recurrence,” in civilization after civilization, of the same inventions and discoveries, the same “dark ages” of slow economic and cultural accumulation, the same rebirths of learning and science and art. No doubt some popular myths are vague traditions surviving from earlier cultures. So the story of man runs in a dreary circle, because he is not yet master of the earth that holds him.
Many of Aristotle’s postulates are arbitrary but he makes brilliant observations at many places, especially in the area of meteorology.
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3. The Foundation of Biology
As Aristotle walked wondering through his great zoological garden, he became convinced that the infinite variety of life could be arranged in a continuous series in which each link would be almost indistinguishable from the next. In all respects, whether in structure, or mode of life, or reproduction and rearing, or sensation and feeling, there are minute gradations and progressions from the lowest organisms to the highest. At the bottom of the scale we can scarcely divide the living from the “dead”; “nature makes so gradual a transition from the inanimate to the animate kingdom that the boundary lines which separate them are indistinct and doubtful”; and perhaps a degree of life exists even in the inorganic. Again, many species cannot with certainty be called plants or animals. And as in these lower organisms it is almost impossible at times to assign them to their proper genus and species, so similar are they; so in every order of life the continuity of gradations and differences is as remarkable as the diversity of functions and forms. But in the midst of this bewildering richness of structures certain things stand out convincingly: that life has grown steadily in complexity and in power; that intelligence has progressed in correlation with complexity of structure and mobility of form; that there has been an increasing specialization of function, and a continuous centralization of physiological control. Slowly life created for itself a nervous system and a brain; and mind moved resolutely on towards the mastery of its environment.
One of the brilliant observations is that there are minute gradations and progressions from the lowest organisms to the highest. Life has grown steadily in complexity and in power.
The remarkable fact here is that with all these gradations and similarities leaping to Aristotle’s eyes, he does not come to the theory of evolution. He rejects Empedocles’ doctrine that all organs and organisms are a survival of the fittest, and Anaxagoras’ idea that man became intelligent by using his hands for manipulation rather than for movement; Aristotle thinks, on the contrary, that man so used his hands because he had become intelligent. Indeed, Aristotle makes as many mistakes as possible for a man who is founding the science of biology. He thinks, for example, that the male element in reproduction merely stimulates and quickens; it does not occur to him (what we now know from experiments in parthenogenesis) that the essential function of the sperm is not so much to fertilize the ovum as to provide the embryo with the heritable qualities of the male parent, and so permit the offspring to be a vigorous variant, a new admixture of two ancestral lines. As human dissection was not practiced in his time, he is particularly fertile in physiological errors: he knows nothing of muscles, not even of their existence; he does not distinguish arteries from veins; he thinks the brain is an organ for cooling the blood; he believes, forgivably, that man has more sutures in the skull than woman; he believes, less forgivably, that man has only eight ribs on each side; he believes, incredibly, and unforgivably, that woman has fewer teeth than man. Apparently his relations with women were of the most amicable kind.
Aristotle rejected earlier doctrines of evolution. As human dissection was not practiced in his time, he is particularly fertile in physiological errors.
Yet he makes a greater total advance in biology than any Greek before or after him. He perceives that birds and reptiles are near allied in structure; that the monkey is in form intermediate between quadrupeds and man; and once he boldly declares that man belongs in one group of animals with the viviparous quadrupeds (our “mammals”). He remarks that the soul in infancy is scarcely distinguishable from the soul of animals. He makes the illuminating observation that diet often determines the mode of life; “for of beasts some are gregarious, and others solitary—they live in the way which is best adapted to… obtain the food of their choice.” He anticipates Von Baer’s famous law that characters common to the genus (like eyes and ears) appear in the developing organism before characters peculiar to its species (like the “formula” of the teeth), or to its individual self (like the final color of the eyes); and he reaches out across two thousand years to anticipate Spencer’s generalization that individuation varies inversely as genesis—that is that the more highly developed and specialized a species or an individual happens to be, the smaller will be the number of its offspring. He notices and explains reversion to type—the tendency of a prominent variation (like genius) to be diluted in mating and lost in successive generations. He makes many zoological observations which, temporarily rejected by later biologists, have been confirmed by modern research—of fishes that make nests, for example, and sharks that boast of a placenta.
Yet Aristotle makes a greater total advance in biology than any Greek before or after him.
And finally he establishes the science of embryology. “He who sees things grow from their beginning,” he writes, “will have the finest view of them.” Hippocrates (b. 460 B. C.), greatest of Greek physicians, had given a fine example of the experimental method, by breaking a hen’s eggs at various stages of incubation; and had applied the results of these studies in his treatise “On the Origin of the Child.” Aristotle followed this lead and performed experiments that enabled him to give a description of the development of the chick which even today arouses the admiration of embryologists. He must have performed some novel experiments in genetics, for he disproves the theory that the sex of the child depends on what testis supplies the reproductive fluid, by quoting a case where the right testis of the father had been tied and yet the children had been of different sexes. He raises some very modern problems of heredity. A woman of Elis had married a negro; her children were all whites, but in the next generation negroes reappeared; where, asks Aristotle, was the blackness hidden in the middle generation? There was but a step from such a vital and intelligent query to the epochal experiments of Gregor Mendel (1822-1882). Prudens quaestio dimidium scientioe—to know what to ask is already to know half. Surely, despite the errors that mar these biological works, they form the greatest monument ever raised to the science by any one man. When we consider that before Aristotle there had been, so far as we know, no biology beyond scattered observations, we perceive that this achievement alone might have sufficed for one life-time, and would have given immortality. But Aristotle had only begun.
Aristotle made many vital and intelligent queries that later led to great discoveries.
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