CHAPTER VIII.
THE BIOLOGY OF ARISTOTLE.
The word “Biology” is perhaps only about fifty years old, having first come into prominent use in the ‘Positive Philosophy’ of Auguste Comte. It is now quite naturalised in the vocabulary of science; and there is an article on “Biology,” by Professor Huxley, in the recently published edition of the ‘Encyclopædia Britannica,’ which begins, “The Biological sciences are those which deal with the phenomena manifested by living matter.” Yet still, in the eyes of a scholar this modern compound is an unfortunate one. The Greeks had two words for life, Zöé and Bios: the former expressed life viewed from the inside, as it were—the vital principle, the functions of life, the sense of living; the latter expressed the external form and manner of living, such as a man’s profession or career. Zöé was applicable to the whole animated kingdom; Bios was restricted to man, except so far as, half-metaphorically, it was applied to the habits of beasts or birds. Thus Aristotle divided Zöé into the species “vegetable,” “animal,” and “human;” but Bios into the species “life of pleasure,” “life of ambition,” and “life of thought.” From all this, it will be seen that “Biology” could not be used to denote a science of the phenomena of living matter in general, without a sacrifice of ancient Greek associations. “Biology,” in short, is more appropriate to express what we generally call Sociology; and, on the other hand, “Zoölogy” should have been used to express what is now called “Biology.” But the fact was, that the word “Zoölogy” (derived from Zöon, an animal, not from Zöé, life) had been already appropriated as a name for natural history. Hence, without regard to classical propriety, the word “Biology” was forced into service to meet a want, and to express, what had never been expressed before, the science of life in all its manifestations from the lowest ascidian up to the highest development of humanity, so far as that development can be considered to be a natural evolution out of the physiological laws of life.
Aristotle had no word to express this comprehensive idea, but assuredly he had the idea itself. He regards the whole of nature as a continuous chain, even beginning with inorganic substances and passing by imperceptible gradations on to organisms, to the vegetable, and to the zoophyte, and then to the animal and the various ranks in the animal kingdom, and lastly to man (‘Researches about Animals,’ VIII. i. 4), “whose soul in childhood, you might say, differs not from the soul of the lower animals.” This broad comprehensive sweep of the philosophic eye through the realms of nature, this finding of unity in such endless diversity, this tracing of a continuous thread throughout the ascending scale of life, may seem quite a matter of course to educated persons of the present day. But it was creditable to Aristotle to have so fully arrived at and entertained this conception, and to have set it forth in such firmly-drawn scientific outlines, Above all, it was creditable to one who, though born of the race of Esculapius (see above, p. 3), had been trained as a dialectician and an orator, and had devoted so much time and labour to the sciences connected with words and thoughts, that he should have had the force and versatility to act also as pioneer into a totally different range of inquiries, and to collect such a mass of facts wherewith to fill in his general sketch of animated nature. It is probable that at all periods of his life his studies, observations, and notes upon matters of physical and natural science, ran on side by side with his development of mental and moral philosophy. Some have thought that the period of his residence at the Court of Macedonia, when acting as tutor to Alexander, afforded him peculiar facilities, in the shape of royal menageries and hunters and fowlers under his command, for the collection of materials for his great work on animals. However this may be, there seems no sufficient reason for taking that work itself out of the list of those which were on the stocks and more or less completed during the last thirteen years of his life.
Aristotle’s biological treatises, as briefly specified above (p. 47), consist (1) of the work ‘On the Parts of Animals,’ which contains a distinction still valid in physiology between “tissues” and “organs,” or as Aristotle calls them, “homogeneous” and “unhomogeneous” substances. He traces here, according to his own ideas, the ascent from the inorganic to the organic world: out of heat, cold, wetness, and dryness the four elements are compounded; out of the four elements are formed the homogeneous substances or tissues; out of these are formed the organs, and out of the organs the organised being. All this served as a provisional theory, until superseded by the discoveries of chemistry. Aristotle laid it down as a principle of method (‘Parts of An.,’ I. i. 4), that all which was common to the various species of living beings should be discussed before entering upon their specific differences. Therefore (2) the treatise ‘On the Soul’ followed next in order, and traced out the vital principle through its successive ascending manifestations. To this was appended (3) the ‘Parva Naturalia’ or ‘Physiological Tracts,’ which dealt with some of the functions of living creatures, whether common or special, such as sensation, memory, dreaming, and also with the following pairs of opposites: waking and sleeping, youth and old age, inspiration and expiration, life and death. It was added that there is another pair still to be treated of—namely, health and sickness. The Stagirite, as was natural from his family traditions, always appears to have looked forward to composing a philosophical work on Medicine. But there is no trace of this ever having been achieved.
The 4th book on the list kept still to generalities. This was the short treatise ‘On the Locomotion of Animals,’ which showed how various organs in the various creatures are adapted by nature for this purpose. Next (5) the elaborate treatise ‘On the Generation of Animals’ worked out this subject, illustrating it with a wonderfully copious collection of facts, or supposed facts, and of the opinions of the day; and, lastly (6), the great treatise entitled ‘Researches about Animals,’ formed, as it were, the conclusion of the whole, by giving detailed observations upon many of the various living creatures which are the products of the working of nature’s general laws.
Aristotle justly drew a distinction between the way in which any phenomenon of nature would be considered and defined by a dialectician and by a physicist. Thus he says (‘On the Soul,’ I. i. 16): “Anger would be defined by a dialectician to be ‘a desire for retaliation,’ or something of the kind,—by a physical philosopher it would be defined as ‘a boiling up of the hot blood about the heart.’” It is needless to say that the Stagirite himself was great and unrivalled in his dialectical definitions,—those definitions which depended on grasping the essence of facts which are patent to all ages alike; while in his physical definitions, being destitute of facts which only later ages have brought to light, he was very imperfect and occasionally almost absurd. As a specimen of this we may mention his account of the vital principle or life, from the two points of view. He defines the vital principle (‘Soul,’ II. i. 6) to be “the essential actuality of an organism;” and this definition has met with high praise from modem physiologists, some of whom, indeed, appear simply to have repeated it in slightly different words. Thus Duges defines life as “the special activity of organised bodies;” and Beclard calls it “organisation in action.”[1] The merit of Aristotle’s definition, as coming from an ancient Greek philosopher, consists in its avoiding the view which would have been natural in those times—namely, that life, the vital principle or the physical soul, was a separate entity, dwelling in the body, hospes comesque corporis, “the body’s guest and friend,” as the Emperor Hadrian called it in his dying verses. Aristotle said that life, or the soul, is not a chance guest, but a function; it is to the body as sight is to the eye; it is the perfect action of all the conditions of the bodily organisation. Thus the Pythagoreans spoke vainly when they talked of the “transmigration of souls,” as if the soul of a man could migrate into the body of a beast. “You might as well,” said Aristotle, “speak of the carpenter’s art (which is the result of the carpenter’s tools) migrating into flutes, which are the tools of the musician.”
So much for his dialectical, or speculative, views of life. The following are some of his opinions in detail on the same subject, from a physical point of view, taken from the ‘Physiological Tracts:’—The primary condition of life is the “natural fire” which resides in the heart of each living creature. This fire may be extinguished by contrary forces, or smothered by excess of heat. Respiration is the process of cooling, which prevents the smothering of the vital fire. Animals require two things for existence—food and cooling. The mouth serves for both purposes, except in the case of fishes,[2] who get their cooling not by air through the lungs, but by water through the gills. The heart is placed in the middle region of the body, and is not only the seat of life, but also of intelligence; it is the first formed of all the parts. The brain is the coldest and wettest part of the body, and serves conjointly with the respiration in cooling down the fire of life. Three of the senses—sight, sound, and smell—are located in the brain; touch and taste reside in the heart, which also contains the “common sensorium,” or faculty of complex perceptions, such as figure, size, motion, and number. The heart makes the blood and sends it out by the “veins” to all parts of the body (of course Aristotle was unaware of the return of the blood to the heart, and therefore made no distinction between veins and arteries). Adequate warmth being the condition of life, the inhabitants of hot countries are longer-lived than those of cold countries; and men are longer-lived than women. But as cooling also is required, people with large heads, as a rule, live long.
It is hardly necessary to say that every opinion above mentioned is mistaken, and almost every statement of fact erroneous. Aristotle, however, is not solely responsible for the doctrines, for he doubtless inherited his ideas of anatomy and physiology from Hippocrates and his father Nicomachus, and, in short, from his Greek predecessors. He neither did, nor could, create the whole of physiology afresh, as he created the whole science of logic. This shows the difference between a science that is simple and abstract, being dependent on a few laws of the human mind, and a science which is infinitely complex, being dependent on facts which have only gradually been discovered up to a certain point during the long lapse of centuries, with the aid of instruments which were unknown to the ancients. But Aristotle had distinctly the idea of the advance of physiology and medicine by means of the study of nature. He said, “Physical philosophy leads to medical deductions, the best doctors seek grounds for their art in nature.” Perhaps from this sentence, at all events from the notion contained in it, the word “physician” has come to be appropriated in modern times by the practitioners of medicine.
Unfortunately, Aristotle not unfrequently applied dialectical reasonings to questions of physiology when they were quite inappropriate. Por instance, arguing against Plato’s theory of respiration—namely, that breathing results from the impact upon us of the external atmosphere following upon the disturbance which is caused by the expiration of warm air—he says that this would imply expiration to be the first of the two operations; but they alternate, and expiration is the last, therefore inspiration must be the first! Again, he mentions the opinion of those who said that the senses correspond with the four elements, and that sight is fire, trying to prove it by the fact that if the eye be struck sparks are seen. Aristotle, however, says that this fact is to be explained in another way: the iris of the eye shines like a phosphorescent substance; when the eye is struck, the sudden shock of the blow causes the eye as an object of vision to become separate from the eye as the organ of vision, and thus the eye for an instant sees itself! Again, he says that the “white” of the eye is unctuous, which prevents the watery vehicle that conveys the sight from getting frozen; the eye is less liable to freeze than any part of the body!
Turning from these curiosities of an old-world physiology, let us glance at the natural history of Aristotle. There is something peculiar and Aristotelian about the very terms “Natural History.” They arise out of a mistranslation of the title of Aristotle’s work, “Histories about Animals,’ where “Histories” is used in its primitive sense of “investigations” or “researches.” But the title has been translated Historia Animalium, or ‘History of Animals,’ and from this the modem phrase “Natural History” has doubtless got crystallised into its present signification. Looking to the contents of the treatise in question, we perceive that to a great part of it the shorter form of the word “Histories” would have been applicable, as consisting rather of “Stories about Animals” than of any very profound investigations with regard to them. It is probable that a large proportion of what is here recorded came to Aristotle orally; and that, too, not from savants, but from uneducated classes of people whose occupations had put them in the way of observing the habits of certain species—such people as fishermen, sailors, sponge-divers, fowlers, hunters, herdsmen, bee-keepers, and the like. We know how difficult it is to get pure fact, unalloyed by fancy, from informants of this kind; and therefore it is no wonder that Aristotle, in compiling the first treatise on Natural History that was ever written, and in collecting his materials by inquiry made at first or second hand from the working classes, should have admitted many a “yarn” and many a “traveller’s tale” into his pages. The subject was too new to admit of his being able by instinctive sagacity to reject the improbable; a judgment of that kind is only attained by one who possesses a vast stock of well-ascertained facts, and by unconscious analogy can argue from the known to the unknown. In many cases Aristotle shows himself almost as simple as old Herodotus, with his tales of the phoenix and other marvels.
The following may be quoted as one instance out of many of the naïveté of the Stagirite (‘Animals,’ IX. xlviii.): “Among marine animals there are many instances recorded of the mild, gentle disposition of the dolphin, and of its love of its children, and its affection, in the neighbourhood of Tarentum, Caria, and other places. It is said that when a dolphin was captured and wounded on the coast of Caria, a great multitude of dolphins came into the harbour, until the fisherman let him go, when they all went away together. And one large dolphin always follows the little ones to take care of them. And sometimes a shoal of large and small dolphins has been seen together, and two of these having been left behind have appeared soon after supporting and carrying on their back a small dead dolphin that was on the point of sinking, as if in pity for it, that it might not be devoured by any other creature. Incredible things are told of the swiftness of the dolphin, which appears to be the swiftest of all animals whether marine or terrestrial. They even leap over the masts of large ships. This is especially the case when they pursue a fish for the sake of food; for if it flies from them they will pursue it, from hunger, into the depths of the sea. And when they have to return from a great depth, they hold in their breath, as if calculating the distance, and gathering themselves up they shoot forward like an arrow, wishing with all speed to accomplish the distance to their breathing-place. And if a ship happen to be in the way, they will leap over its masts. The males and females live in pairs with each other. There is some doubt why they cast themselves on shore, for it is said that they do this at times without any apparent reason.”
The freshness of spirit which breathes through this passage characterises the whole of Aristotle’s treatise, which, in spite of its sometimes reminding us of the “showman” of modern times, has excited the enthusiastic admiration of several great authorities. Cuvier says, “I cannot read this work without being ravished with astonishment. Indeed it is impossible to conceive how a single man was able to collect and compare the multitude of particular facts implied in the numerous rules and aphorisms which are contained in this book.” Buifon, De Blainville, St Hilaire, and others,[3] have used similar terms of eulogy. One modern zoologist, Professor Sundevall of Stockholm, has reckoned up the number of species with which Aristotle showed himself to be more or less acquainted, and he finds them to amount to nearly 500,—the total number of mammals described or indicated being about 70; of birds 150; of reptiles 20; and of fishes 116—making altogether 356 species of vertebrate animals. Of the invertebrate classes about 60 species of insects and arachnids seem to have been known to Aristotle; some 24 crustaceans and annelids; and about 40 molluscs and radiates,[4] At the same time, it must be remembered that Aristotle had no idea of the scientific system of classification which appears in Professor Sundevall’s list. He does not seem to have laboured much at the arrangement of living creatures into natural orders; indeed he could not have succeeded in such an attempt, for want of a sufficient knowledge of anatomy. He was content with the superficial, universally-received, grouping of animals, as walking, creeping, flying, or swimming; as oviparous or viviparous; aquatic or terrestrial; and the like. His book contains a mass of materials, but without much methodic arrangement or trace of system. It pointed the way, however, for his successors to a science of zoology.
The facts given by him of course vary extremely in correctness and in value. In his account of sponges, for instance, Aristotle is thought to have shown sound information, probably derived from the reports of the professional divers. But his statements about bees, though obtained, as he tells us, from bee-keepers, and though “made beautiful for ever” in the charming verses of Virgil’s fourth Georgic, have been quite overturned by the microscopic discoveries of Reaumur, Hunter, Huber, Keys, Vicat, and Dunbar. On one cardinal point the ancients were all wrong: they did not understand the sex and the functions of either the queen-bee, the worker, or the drone.
The following account of the lion is considered to be fairly correct (‘An.,’ IX. xliv.): “When feeding, the lion is extremely savage; but when he is not hungry and is full fed, he is quite gentle. He is not either jealous or suspicious. He is playful and affectionate towards those animals which have been brought up with him, and to which he is accustomed. When hunted, so long as he is in view he never flies or cowers; and if compelled to give way by the number of his hunters, he retreats leisurely, at a walk, turning himself round at short intervals. But if he reaches a covert he flies rapidly, until he is in the open again, and then he again retreats at a walk. If compelled to fly when on the open plains, he runs at full stretch, but does not leap. His manner of running is continuous, like that of a dog at full stretch; when pursuing his prey, however, he throws himself upon it when he comes within reach. It is true what they say about the lion being very much afraid of fire (as Homer wrote, ‘the blazing fagots, that his courage daunt’), and about his watching and singling out for attack the person who has struck him. But when any one misses hitting him and only annoys him, if in his rush he succeeds in catching that person, he does not harm him nor wound him with his claws, but shakes and frightens him and then leaves him. Lions are more disposed to enter towns and attack mankind when they have grown old, because old age renders them unable to hunt, and because of the decay of their teeth. They live many years; and in the case of a lame lion who was captured, he had many of his teeth worn down, which some considered a sign that lions live long, for this could not have happened to an animal who was not aged.”
The ‘Researches about Animals,’ like many other of Aristotle’s great treatises, appears to have been left in an unfinished state. The tenth book seems merely to be a sort of fragmentary continuation of the seventh book—both treating of the reproduction of the human species. In the ten books as they have come down to us, no one can pretend to find a finished whole. It is a question, therefore, whether the work was ever published in Aristotle’s lifetime, or whether it ever got, in its present form, to the Alexandrian Library. In the Alexandrian Catalogue, indeed, there is mention of a work entitled ‘Animals’ in nine books. But this may have been a set of excerpts by some Peripatetic scholar; we cannot tell what its exact relation to “Our Aristotle” may have been. There is some little interest in the question, on account of the influence that Aristotle is supposed to have exercised on the Septuagint version of the Old Testament, which was begun at Alexandria 285 b.c.—that is to say, just after Aristotle’s MSS had been carried off to Asia Minor. It has been conjectured that the Septuagint translators, in rendering the Hebrew word arnebeth, or "hare," by the Greek word dasypus (hairy-foot), instead of by the word lagos, which had been usual in earlier classical Greek, were following a new fashion set by Aristotle in his 'Researches about Animals,' in which work "the modern word dasypus had almost entirely superseded the older."[5] And it is added that "there was an even yet more striking example of Aristotle's influence on the passage" (Leviticus, xi. 6): for whereas in the original Hebrew text the hare was said to chew the cud, the translators, having been enlightened by the natural history of Aristotle, "boldly interpolated the word not into the sacred text." The facts of the case are—that Aristotle uses lagos for "hare" indifferently with, and nearly as often as, dasypus; and that in one passage ('An.,' III. xxi. 1) he cursorily contrasts the hare with the class of ruminants. On the whole, then, it seems most natural to believe that the Septuagint translators used the word dasypus because it had become the fashion in speaking Greek to use it, and that Aristotle himself had obeyed and not created this fashion. With regard to the other point, it is quite possible that the translators may have seen that passage of Aristotle's above referred to; at all events, as educated men, they were doubtless influenced by the spread of the study of natural history, to which Aristotle, who had died only thirty-seven years before, had given great impetus.
- ↑ These definitions are quoted in Bennett’s ‘Text-book of Physiology,’ p. 184. See also Mr G. H. Lewes’s ‘Aristotle, a Page from the History of Science,’ p. 230.
- ↑ Aristotle rejects the (true) opinion of Anaxagoras and Diogenes that fishes get air out of the water which they draw through their gills, and that they are suffocated when out of the water because the air comes to them in too large quantities.
- ↑ Quoted by Mr G. H. Lewes in his ‘Aristotle,’ p. 270.
- ↑ See ‘The Natural History Review’ for 1864, p. 494.
- ↑ Dean Stanley's 'Lectures on the History of the Jewish Church,' iii. 261.