Some of these stories are indeed remarkable, for the events related are more or less hidden and obscure; and so, with all this knowledge at hand, it is not a little strange that Aristotle has very little indeed to tell us about the far more obvious phenomena of the life-history of the butterfly, and of the several kinds of butterflies and moths. He does tell us briefly that the butterfly comes from a caterpillar, which lives on cabbage-leaves and feeds voraciously, then turns into a chrysalis and eats no more, nor has it a mouth to eat withal; it is hard and, as it were, dead, but yet it moves and wriggles when you touch it, and after a while the husk bursts and out comes the butterfly. The account is good enough, so far as it goes, but nevertheless Aristotle shows no affection for the butterfly, does not linger and dally over it, tells no stories about it. This is all of a piece with the rest of Greek literature, and poetry in particular, where allusions to the butterfly are scanty and rare. I think the Greeks found something ominous or uncanny, something not to be lightly spoken of, in that all but disembodied spirit which we call a butterfly, and they called by the name of ψυχη, the Soul. They had a curious name (νεκυδαλλος) for the pupa. It sounds like a ‘little corpse’ (νεκυς); and like a little corpse within its shroud or coffin the pupa sleeps in its cocoon. A late poet describes the butterfly ‘coming back from the grave to the light of day’; and certain of the Fathers of the Church, St. Basil in particular, point the moral accordingly, and draw a doubtless time-honoured allegory of the Resurrection and the Life from the grub which is not dead but sleepeth, and the butterfly which (as it were) is raised in glory.
Of one large moth, Aristotle gives us an account which has been a puzzle to many. This begins as a great grub or caterpillar, with (as it were) horns; and, growing by easy stages, it spins at length a cocoon. There is a class of women who unwind and reel off the cocoons, and afterwards weave a fabric with the thread; and a certain woman of Cos is credited with the invention of this fabric. This is, at first sight, a plain and straightforward description of the silkworm; but we know that it was not till long afterwards, nearly a thousand years after, in Justinian’s reign, that the silkworm and the mulberry-tree which is its food were brought out of the East into Byzantine Greece. We learn something of this Coan silkworm from Pliny, who tells us that it lived on the ash and oak and cypress tree; and from Clement of Alexandria and other of the Fathers we glean a little more—for instance, that the larva was covered with thick-set hairs, and that the cocoon was of a loose material something like a spider’s web. All this agrees in every particular with a certain large moth (Lasiocampa otus), which spins a rough cocoon not unlike that of our Emperor moth, and lives in south-eastern Europe, feeding on the cypress and the oak. Many other silkworms besides the true or common one are still employed, worms which yield the Tussore silks of India and other kindred silks in Japan; and so likewise was this rough silky fabric spun and woven in Hellas, until in course of time it was surpassed and superseded by the finer produce of the ‘Seric worm’, and the older industry died out and was utterly forgotten.
Ere we leave the subject of insects let us linger a moment over one which the Greeks loved, and loved most of all. When as schoolboys we first began to read our Thucydides, we met in the very beginning with the story of how rich Athenians wore Golden Grasshoppers (as the schoolmaster calls them) in their hair. These golden ornaments were, of course, no common grasshoppers, but the little Cicadas, whose sharp chirrup seemed delightful music to the Greeks. It is unpleasant to our ears, as Browning found it; but in a multitude of Greek poets, in Alcaeus and Anacreon and all through the whole Anthology, we hear its praise. We have it, for instance, in the Birds:
Though the hot sun be shining in the sky
In the deep flowery meadow-grass I lie:
To listen to the shrill melodious tune
Of crickets, thrilled to ecstasy at noon.
Of this familiar and beloved insect Aristotle gives a copious account. He describes two separate species, which we still recognize easily; a larger one and the better singer, the other smaller and the first to come and last to go with the summer season. He recognized the curious vocal organ, or vibratory drum, at the cicada’s waist, and saw that some cicadas possessed it and others not; and he knew, as the poets also knew, that it was the males who sang, while their wives listened and were silent. He tells how the cicada is absent from treeless countries, as, for instance, from Cyrene (and why, I wonder, does he go all the way to Cyrene for his illustration?), neither is it heard in deep and sunless woods; but in the olive-groves you hear it at its best, for an olive-grove is sparse and the sun comes through. Then he tells us briefly, but with remarkable accuracy, the story of the creature’s life: how the female, with her long ovipositor, lays her eggs deep down in dead, hollow twigs, such as the canes on which the vines are propped; how the brood, when they escape from the egg, burrow underground; how later on they emerge, especially in rainy weather, when the rains have softened the soil; how then the larva changes into another form, the so-called ‘nymph’; and how at last, when summer comes, the skin of the nymph breaks and the perfect insect issues forth, changes colour, and begins to sing. In Aristophanes, in Theocritus, in Lucretius, Virgil, Martial, and in the Anthology, we may gather up a host of poetical allusions to the natural history thus simply epitomized.
The Book about Animals, the Historia Animalium as we say, from which I have quoted these few examples of Aristotle’s store of information, may be taken to represent the first necessary stage of scientific inquiry. There is a kind of manual philosophy (as old Lord Monboddo called it) which investigates facts which escape the vulgar, and may be called the anecdotes or secret history of nature. In this fascinating pursuit Gilbert White excelled, and John Ray and many another—the whole brotherhood of simple naturalists. But such accumulated knowledge of facts is but the foundation of a philosophy; and ‘nothing deserves the name of philosophy, except what explains the causes and principles of things’. Aristotle would have done much had he merely shown (as Gilbert White showed to the country gentlemen of his day) that the minute observation of nature was something worth the scholar and the gentleman’s while; but, far more than this, he made a Science of natural knowledge, and set it once for all within the realm of Philosophy. He set it side by side with the more ancient science of Astronomy, which for many hundred years in Egypt and the East, and for some few centuries in Hellas, had occupied the mind of philosophers and the attention of educated men. I have quoted before a great sentence in which he explains his purpose, and makes excuse for his temerity. ‘The glory, doubtless, of the heavenly bodies fills us with more delight than the contemplation of these lowly things; for the sun and stars are born not, neither do they decay, but are eternal and divine. But the heavens are high and afar off, and of celestial things the knowledge that our senses give us is scanty and dim. The living creatures, on the other hand, are at our door, and if we so desire it we may gain ample and certain knowledge of each and all. We take pleasure in the beauty of a statue, shall not then the living fill us with delight; and all the more if in the spirit of philosophy we search for causes and recognize the evidences of design. Then will nature’s purpose and her deep-seated laws be everywhere revealed, all tending in her multitudinous work to one form or another of the Beautiful.’
Aristotle’s voluminous writings have come down to us through many grave vicissitudes. The greatest of them all are happily intact, or very nearly so; but some are lost and others have suffered disorder and corruption. The work known as the ‘Parts of Animals’ opens (as our text has it) with a chapter which seems meant for a general exordium to the whole series of biological treatises; and I know no chapter in all Aristotle’s books which better shows (in plainer English or easier Greek) the master-hand of the great Teacher and Philosopher. He begins by telling us (it has ever since been a common saying) that every science, every branch of knowledge, admits of two sorts of proficiency—that which may properly be termed scientific knowledge, and that which is within the reach of ordinary educated men. He proceeds to discuss the ‘method’ of scientific inquiry, whether we should begin with the specific and proceed to the general, or whether we are to deal first with common or generical characters and thereafterward with special peculiarities. Are we entitled to treat of animals, as is done in mathematical astronomy, by dealing first with facts or phenomena and then proceeding to discover and relate their several causes? At once this leads to a brief discussion (elaborated elsewhere) of the two great Causes, or aspects of cause—the final cause and the ‘moving’ or efficient cause—the reason why or the purpose for which, and the antecedent cause which, of necessity, brings a thing to be such as it is. Here is one of the great crucial questions of philosophy, and Aristotle’s leaning to the side of the Final Cause has been a dominant influence upon the minds of men throughout the whole history of learning. Empedocles had taken another view: he held that the rain comes when it listeth, or ‘of necessity’; that we have no right to suppose it comes to make the corn grow in spring, any more than to spoil the autumn sheaves: that the teeth grow by the operation of some natural (or physical) law, and that their apparent and undoubted fitness for cutting and grinding is not purposeful but coincident; that the backbone is divided into vertebrae because of the antecedent forces, or flexions, which act upon it in the womb. And Empedocles proceeds to the great evolutionary deduction, the clear prevision of Darwin’s philosophy, that fit and unfit arise alike, but that what is fit to survive does survive and what is unfit perishes.
The story is far too long and the theme involved too grave and difficult for treatment here. But I would venture to suggest that Aristotle inclined to slur over the physical and lean the more to the final cause, for this simple reason (whatever other reasons there may be), that he was a better biologist than a physicist: that he lacked somewhat the mathematical turn of mind which was intrinsic to the older schools of philosophy. For better for worse the course he took, the choice he made, was of incalculable import, and had power for centuries to guide (dare we say, to bias) the teaching of the schools, the progress of learning, and the innermost beliefs of men.
In this one short but pregnant chapter of Aristotle’s there is far more than we can hope even to epitomize. He has much to say in it of ‘classification’, an important matter indeed, and he discusses it as a great logician should, in all its rigour. Many commentators have sought for Aristotle’s ‘classification of animals’; for my part I have never found it, and, in our sense of the word, I am certain it is not there. An unbending, unchanging classification of animals would have been something foreign to all his logic; it is all very well, it becomes practically necessary, when we have to arrange our animals on the shelves of a museum or in the arid pages of a ‘systematic’ catalogue; and it takes a new complexion when, or if, we can attain to a real or historical classification, following lines of actual descent and based on proven facts of historical evolution. But Aristotle (as it seems to me) neither was bound to a museum catalogue nor indulged in visions either of a complete scala naturae or of an hypothetical phylogeny. He classified animals as he found them; and, as a logician, he had a dichotomy for every difference which presented itself to his mind. At one time he divided animals into those with blood and those without, at another into the air-breathers and the water-breathers; into the wild and the tame, the social and the solitary, and so on in endless ways besides. At the same time he had a quick eye for the great natural groups, such ‘genera’ (as he called them) as Fish or Bird, Insect or Mollusc. So it comes to pass that, while he fashioned no hard and fast scheme of classification, and would undoubtedly (I hold) have thought it vain to do so, the threads of his several partial or temporary classifications come together after all, though in a somewhat hazy pattern, yet in a very beautiful and coherent parti-coloured web. And though his order is not always our order, yet a certain exquisite orderliness is of the very essence of his thought and style. It is the characteristic which Molière hits upon in Les Femmes savantes,—‘Je m’attache pour l’ordre au péripatétisme’.
Before he finishes the great chapter of which we have begun to speak he indicates that there are more ways than one of relating, or classifying, our facts; that, for instance, it may be equally proper and necessary to deal now with the animals and their several parts or properties, and at another time with the parts or properties as such, explaining and illustrating them in turn by the several animals which display or possess them. The ‘Parts of Animals’ is, then, a corollary, a necessary corollary, to the more anecdotal Historia Animalium. And yet again, there is a third alternative—to discuss the great functions or actions or potentialities of the organism, as it were first of all in the abstract, and then to correlate them with the parts which in this or that creature are provided and are ‘designed’ to effect them. This involves the conception and the writing of separate physiological treatises on such themes as Respiration, Locomotion, on Sleeping and Waking, and lastly (and in some respects the most ambitious, most erudite, and most astonishing of them all) the great account of the Generation of Animals.