Book VIII

of his _Collection_.

We come, lastly, to Algebra. Problems involving simple equations are found in the Papyrus Rhind, in the _Epanthema_ of Thymaridas already referred to, and in the arithmetical epigrams in the Greek Anthology (Plato alludes to this class of problem in the _Laws_, 819 B, C); the Anthology even includes two cases of indeterminate equations of the first degree. The Pythagoreans gave general solutions in rational numbers of the equations _x²+y²=z²_ and _2x²-y²=±1_, which are indeterminate equations of the second degree.

The first to make systematic use of symbols in algebraical work was Diophantus of Alexandria (fl. about A. D. 250). He used (1) a sign for the unknown quantity, which he calls αριθμος {arithmos}, and compendia for its powers up to the sixth; (2) a sign ([Transcriber's Note: Symbol]) with the effect of our _minus_. The latter sign probably represents ΛΙ {LI}, an abbreviation for the root of the word λειπειν {leipein} (to be wanting); the sign for αριθμος {arithmos} ([Transcriber's Note: Symbol]) is most likely an abbreviation for the letters αρ {ar}; the compendia for the powers of the unknown are Δ^Υ {D^Y} for δυναμις {dynamis}, the square, Κ^Υ {K^Y} for κυβος {kybos}, the cube, and so on. Diophantus shows that he solved quadratic equations by rule, like Heron. His _Arithmetica_, of which six books only (out of thirteen) survive, contains a certain number of problems leading to simple equations, but is mostly devoted to indeterminate or semi-determinate analysis, mainly of the second degree. The collection is extraordinarily varied, and the devices resorted to are highly ingenious. The problems solved are such as the following (fractional as well as integral solutions being admitted): 'Given a number, to find three others such that the sum of the three, or of any pair of them, together with the given number is a square', 'To find four numbers such that the square of the sum _plus_ or _minus_ any one of the numbers is a square', 'To find three numbers such that the product of any two _plus_ or _minus_ the sum of the three is a square'. Diophantus assumes as known certain theorems about numbers which are the sums of two and three squares respectively, and other propositions in the Theory of Numbers. He also wrote a book _On Polygonal Numbers_ of which only a fragment survives.

With Pappus and Diophantus the list of original writers on mathematics comes to an end. After them came the commentators whose names only can be mentioned here. Theon of Alexandria, the editor of Euclid, lived towards the end of the fourth century A. D. To the fifth and sixth centuries belong Proclus, Simplicius, and Eutocius, to whom we can never be grateful enough for the precious fragments which they have preserved from works now lost, and particularly the _History of Geometry_ and the _History of Astronomy_ by Aristotle's pupil Eudemus.

Such is the story of Greek mathematical science. If anything could enhance the marvel of it, it would be the consideration of the shortness of the time (about 350 years) within which the Greeks, starting from the very beginning, brought geometry to the point of performing operations equivalent to the integral calculus and, in the realm of astronomy, actually anticipated Copernicus.

T. L. HEATH.

NATURAL SCIENCE

_Aristotle_

There is a little essay of Goethe's called, simply, _Die Natur_. It comes among those tracts on Natural Science in which the poet and philosopher turned his restless mind to problems of light and colour, of leaf and flower, of bony skull and kindred vertebra; and it sounds like a prose-poem, a noble paean, eulogizing the love and glorifying the study of Nature. Some twenty-five hundred years before, Anaximander had written a book with the same title, _Concerning Nature_, περι φυσεως {peri physeôs}: but its subject was not the same. It was a variant of the old traditional cosmogonies. It told of how in the beginning the earth was without form and void. It sought to trace all things back to the Infinite, το απειρον {to apeiron}--to That which knows no bounds of space or time but is before all worlds, and to whose bosom again all things, all worlds, return. For Goethe Nature meant the beauty, the all but sensuous beauty of the world; for the older philosopher it was the mystery of the Creative Spirit.

Than Nature, in Goethe's sense, no theme is more familiar to us, for whom many a poet tells the story and many a lesser poet echoes the conceit; but if there be anywhere in Greek such overt praise and worship of Nature's beauty, I cannot call it to mind. Yet in Latin the _divini gloria ruris_ is praised and _Natura daedala rerum_ worshipped, as we are wont to praise and worship them, for their own sweet sakes. It is one of the ways, one of the simpler ways, in which the Roman world seems nearer to us than the Greek: and not only seems, but is so. For compared with the great early civilizations, Rome is modern and of the West; while, draw her close as we may to our hearts, Greece brings along with her a breath of the East and a whisper of remote antiquity. A Tuscan gentleman of to-day, like a Roman gentleman of yesterday, is at heart a husbandman, like Cato; he is _ruris amator_, like Horace; he gets him to his little farm or vineyard (_O rus, quando te aspiciam!_), like Atticus or the younger Pliny. As Bacon praised his garden, so does Pliny praise his farm, with its cornfields and meadowland, vineyard and woodland, orchard and pasture, bee-hives and flowers. That God made the country and man made the town was (long before Cowper) a saying of Varro's; but in Greek I can think of no such apophthegm.

As Schiller puts it, the Greeks looked on Nature with their minds more than with their hearts, nor ever clung to her with outspoken admiration and affection. And Humboldt, asserting (as I would do) that the portrayal of nature, for her own sake and in all her manifold diversity, was foreign to the Greek idea, declares that the landscape is always the mere background of their picture, while their foreground is filled with the affairs and actions and thoughts of men. But all the while, as in some old Italian picture--of Domenichino or Albani or Leonardo himself--the subordinated background is delicately traced and exquisitely beautiful; and sometimes we come to value it in the end more than all the rest of the composition.

Deep down in the love of Nature, whether it be of the sensual or intellectual kind, and in the art of observation which is its outcome and first expression, lie the roots of all our Natural Science. All the world over these are the heritage of all men, though the inheritance be richer or poorer here and there: they are shown forth in the lore and wisdom of hunter and fisherman, of shepherd and husbandman, of artist and poet. The natural history of the ancients is not enshrined in Aristotle and Pliny. It pervades the vast literature of classical antiquity. For all we may say of the reticence with which, the Greeks proclaim it, it greets us nobly in Homer, it sings to us in Anacreon, Sicilian shepherds tune their pipes to it in Theocritus: and anon in Virgil we dream of it to the coo of doves and the sound of bees' industrious murmur.

Not only from such great names as these do we reach the letter and the spirit of ancient Natural History. We must go a-wandering into the by-ways of literature. We must eke out the scientific treatises of Aristotle and Pliny by help of the fragments which remain of the works of such naturalists as Speusippus or Alexander the Myndian; add to the familiar stories of Herodotus the Indian tales of Ctesias and Megasthenes; sit with Athenaeus and his friends at the supper table, gleaning from cook and epicure, listening to the merry idle troop of convivial gentlemen capping verses and spinning yarns; read Xenophon's treatise on Hunting, study the didactic poems, the Cynegetica and Halieutica, of Oppian and of Ovid. And then again we may hark back to the greater world of letters, wherein poet and scholar, from petty fabulist to the great dramatists, from Homer's majesty to Lucian's wit, share in the love of Nature and enliven the delicate background of their story with allusions to beast and bird.

Such allusions, refined at first by art and hallowed at last by familiar memory, lie treasured in men's hearts and enshrine themselves in our noblest literature. Take, of a thousand crowding instances, that great passage in the _Iliad_ where the Greek host, disembarking on the plains of the Scamander, is likened to a migrating flock of cranes or geese or long-necked swans, as they fly proudly over the Asian meadows and alight screaming by Cayster's stream--and Virgil echoes more than once the familiar lines. The crane was a well-known bird. Its lofty flight brings it, again in Homer, to the very gates of heaven. Hesiod and Pindar speak of its far-off cry, heard from above the clouds: and that it 'observed the time of its coming', 'intelligent of seasons', was a proverb old in Hesiod's day--when the crane signalled the approach of winter, and when it bade the husbandman make ready to plough. It follows the plough, in Theocritus, as persistently as the wolf the kid and the peasant-lad his sweetheart. The discipline of the migrating cranes, the serried wedge of their ranks in flight, the good order of the resting flock, are often, and often fancifully, described. Aristotle records how they have an appointed leader, who keeps watch by night and in flight keeps calling to the laggards; and all this old story Euripides, the most naturalistic of the great tragedians, puts into verse:

The ordered host of Libyan birds avoids The wintry storm, obedient to the call Of their old leader, piping to his flock.

Lastly, Milton gathers up the spirit and the letter of these and many another ancient allusion to the migrating cranes:

Part loosely wing the region; part more wise, In common ranged in figure, wedge their way Intelligent of seasons, and set forth Their aery caravan, high over seas Flying, and over lands; with mutual wing Easing their flight; so steers the prudent crane.

But the natural history of the poets is a story without an end, and in our estimation, however brief it be, of ancient knowledge, there are other matters to be considered, and other points of view where we must take our stand.

When we consider the science of the Greeks, and come quickly to love it and slowly to see how great it was, we likewise see that it was restricted as compared with our own, curiously partial or particular in its limitations. The practical and 'useful' sciences of chemistry, mechanics, and engineering, which in our modern world crowd the others to the wall, are absent altogether, or so concealed that we forget and pass them by. Mathematics is enthroned high over all, as it is meet she should be; and of uncontested right she occupies her throne century after century, from Pythagoras to Proclus, from the scattered schools of early Hellenic civilization to the rise and fall of the great Alexandrine University. Near beside her sits, from of old, the daughter-science of Astronomy; and these twain were worshipped by the greatest scientific intellects of the Greeks. But though we do not hear of them nor read of them, we must not suppose for a moment that the practical or technical sciences were lacking in so rich and complex a civilization. China, that most glorious of all living monuments of Antiquity, tells us nothing of her own chemistry, but we know that it is there. Peep into a Chinese town, walk through its narrow streets, thronged but quiet, wherein there is neither rumbling of coaches nor rattling of wheels, and you shall see the nearest thing on earth to what we hear of Sybaris. To the production of those glowing silks and delicate porcelains and fine metal-work has gone a vast store of chemical knowledge, traditional and empirical. So was it, precisely, in ancient Greece; and Plato knew that it was so--that the dyer, the perfumer, and the apothecary had subtle arts, a subtle science of their own, a science not to be belittled nor despised. We may pass here and there by diligent search from conjecture to assurance; analyse a pigment, an alloy or a slag; discover from an older record than the Greeks', the chemical prescription wherewith an Egyptian princess darkened her eyes, or study the pictured hearth, bellows, oven, crucibles with which the followers of Tubal-Cain smelted their ore. Once in a way, but seldom, do we meet with ancient chemistry even in Greek literature. There is a curious passage (its text is faulty and the translation hard) in the story of the Argonauts, where Medea concocts a magic brew. She put divers herbs in it, herbs yielding coloured juices such as safflower and alkanet, and soapwort and fleawort to give consistency or 'body' to the lye; she put in alum and blue vitriol (or sulphate of copper), and she put in blood. The magic brew was no more and no less than a dye, a red or purple dye, and a prodigious deal of chemistry had gone to the making of it. For the copper was there to produce a 'lake' or copper-salt of the vegetable alkaloids, which copper-lakes are among the most brilliant and most permanent of colouring matters; the alum was there as a 'mordant'; and even the blood was doubtless there incorporated for better reasons than superstitious ones, in all probability for the purpose of clarifying (by means of its coagulating albumen) the seething and turbid brew.

The 'Orphic' version of the story, in which this passage occurs, is probably an Alexandrine compilation, and whether the ingredients of the brew had been part of the ancient legend or were merely suggested to the poet by the knowledge of his own day we cannot tell; in either case the prescription is old enough, and is at least pre-Byzantine by a few centuries. Such as it is, it does not stand alone. Other fragments of ancient chemistry, more or less akin to it, have been gathered together; in Galen's book on _The making of Simples_, in Pliny, in Paulus Aegineta, and for that matter in certain Egyptian papyri (especially a certain very famous one, still extant, of which Clement of Alexandria speaks as a secret or 'hermetic' book), we can trace the broken and scattered stones of a great edifice of ancient chemistry.

Nevertheless, all this weight of chemical learning figures scantily in literature, and is conspicuously absent from our conception of the natural genius of the Greeks. We have no reason to suppose that ancient chemistry, or any part of it, was ever peculiarly Greek, or that this science was the especial property of any nation whatsoever; moreover it was a trade, or a bundle of trades, whose trade-secrets were too precious to be revealed, and so constituted not a science but a mystery. So has it always been with chemistry, the most cosmopolitan of sciences, the most secret of arts. Quietly and stealthily it crept through the world; the tinker brought it with his solder and his flux; the African tribes who were the first workers in iron passed it on to the great metallurgists who forged Damascan and Toledan steel.

This 'trade' of Chemistry was never a science for a Gentleman, as philosophy and mathematics were; and Plato, greatest of philosophers, was one of the greatest of gentlemen. Long, long afterwards, Oxford said the same thing to Robert Boyle--that Chemistry was no proper avocation for a gentleman; but he thought otherwise, and the 'brother of the Earl of Cork' became the Father of scientific Chemistry.

Now I take it that in regard to biology Aristotle did much the same thing as Boyle, breaking through a similar tradition; and herein one of the greatest of his great services is to be found. There was a wealth of natural history before his time; but it belonged to the farmer, the huntsman, and the fisherman--with something over (doubtless) for the schoolboy, the idler, and the poet. But Aristotle made it a science, and won a place for it in Philosophy. He did for it just what Pythagoras had done (as Proclus tells us) for mathematics in an earlier age, when he discerned the philosophy underlying the old empirical art of 'geometry', and made it the basis of 'a liberal education'.[5]

[5] επι δε τουτοις Πυθαγορας την περι αυτην φιλοσοφιαν εις σχημα παιδειας ελευθερου μετεστησεν. {epi de toutois Pythagoras tên peri autên philosophian eis schêma paideias eleutherou metestêsen.} _Procli Comment. Euclidis lib. I, Prolegom. II_ (p. 65, ed. Friedlein).

The Mediterranean fisherman, like the Chinese fisherman or the Japanese, has still, and always has had, a wide knowledge of all that pertains to and accompanies his craft. Our Scottish fishermen have a limited vocabulary, which scarce extends beyond the names of the few common fishes with which the market is supplied. But at Marseilles or Genoa or in the Levant they have names for many hundreds of species, of fish and shell-fish and cuttle-fish and worms and corallines, and all manner of swimming and creeping things; they know a vast deal about the habits of their lives, far more, sometimes, than do we 'scientific men'; they are naturalists by tradition and by trade. Neither, by the way, must we forget the ancient medical and anatomical learning of the great Aesculapian guild, nor the still more recondite knowledge possessed by various priesthoods (again like their brethren of to-day in China and Japan) of the several creatures, sacred fish, pigeons, guinea-fowl, snakes, cuttlefish, and what not, which time out of mind they had reared, tended, and venerated.

Of what new facts Aristotle actually discovered it is impossible to be sure. Could it ever be proved that he discovered many, or could it even be shown that of his own hand he discovered nothing at all, it would affect but little our estimate of his greatness and our admiration of his learning. He was the first of Greek philosophers and gentlemen to see that all these things were good to know and worthy to be told. This was his great discovery.

I have sought elsewhere to show that Aristotle spent two years, the happiest years perhaps of all his life--a long honeymoon--by the sea-side in the island of Mytilene, after he had married the little Princess, and before he began the hard work of his life: before he taught Alexander in Macedon, and long before he spoke _urbi et orbi_ in the Lyceum. Here it was that he learned the great bulk of his natural history, in which, wide and general as it is, the things of the sea have from first to last a notable predominance.

I have tried to illustrate elsewhere (as many another writer has done) something of the variety and the depth of Aristotle's knowledge of animals--choosing an example here and there, but only drawing a little water from an inexhaustible well.

A famous case is that of the 'molluscs', where either Aristotle's knowledge was exceptionally minute, or where it has come down to us with unusual completeness.

These are the cuttle fish, which have now surrendered their Aristotelian name of 'molluscs' to that greater group which is seen to include them, together with the shell-fish or 'ostracoderma' of Aristotle. These cuttle-fishes are creatures that we seldom see, but in the Mediterranean they are an article of food and many kinds are known to the fishermen. All or wellnigh all of these many kinds were known to Aristotle. He described their form and their anatomy, their habits, their development, all with such faithful accuracy that what we can add to-day seems of secondary importance. He begins with a methodical description of the general form, tells us of the body and fins, of the eight arms with their rows of suckers, of the abnormal position of the head. He points out the two long arms of Sepia and of the calamaries, and their absence in the octopus; and he tells us, what was only confirmed of late, that with these two long arms the creature clings to the rock and sways about like a ship at anchor. He describes the great eyes, the two big teeth forming the beak; and he dissects the whole structure of the gut, with its long gullet, its round crop, its stomach and the little coiled coecal diverticulum: dissecting not only one but several species, and noting differences that were not observed again till Cuvier re-dissected them. He describes the funnel and its relation to the mantle-sac, and the ink-bag, which he shows to be largest in Sepia of all others. And here, by the way, he seems to make one of those apparent errors that, as it happens, turn out to be justified: for he tells us that in Octopus, unlike the rest, the funnel is on the upper side; the fact being that when the creature lies prone upon the ground, with all its arms outspread, the funnel-tube (instead of being flattened out beneath the creature's prostrate body) is long enough to protrude upwards between arms and head, and to appear on one side or other thereof, in a position apparently the reverse of its natural one. He describes the character of the cuttle-bone in Sepia, and of the horny pen which takes its place in the various calamaries, and notes the lack of any similar structure in Octopus. He dissects in both sexes the reproductive organs, noting without exception all their essential and complicated parts; and he had figured these in his lost volume of anatomical diagrams. He describes the various kinds of eggs, and, with still more surprising knowledge, shows us the little embryo cuttle-fish, with its great yolk-sac attached, in apparent contrast to the chick's, to the little creature's developing head.

But there is one other remarkable feature that he knew ages before it was rediscovered, almost in our own time. In certain male cuttle-fishes, in the breeding season, one of the arms develops in a curious fashion into a long coiled whip-lash, and in the act of breeding may then be transferred to the mantle-cavity of the female. Cuvier himself knew nothing of the nature or the function of this separated arm, and indeed, if I am not mistaken, it was he who mistook it for a parasitic worm. But Aristotle tells us of its use and its temporary development, and of its structure in detail, and his description tallies closely with the accounts of the most recent writers.

A scarcely less minute account follows of the 'Malacostraca' or crustaceans, the lobsters and the crabs, the shrimps and the prawns, and others of their kind, a chapter to which Cuvier devoted a celebrated essay. There be many kinds of crabs--the common kind, the big 'granny' crabs, the little horsemen-crabs, that scamper over the sand and which are for the most part empty, that is to say, whose respiratory cavities are exceptionally large; and there are the freshwater crabs. There are the little shrimps and the big hump-backed fellows, or prawns; there are the 'crangons' or squillae; and the big lobsters and the crawfish or 'langoustes', their spiny cousins. We read about their beady eyes, which turn every way; about their big rough antennae and the smaller, smoother pair between; the great teeth, or mandibles; the carapace with its projecting rostrum, the jointed abdomen with the tail-fins at the end, and the little flaps below on which the female drops her spawn. In more or less detail these things are severally described, and the many limbs severally enumerated, in one kind after another. The descriptions of the lobster and the langouste are particularly minute, and the comparison or contrast between the two is drawn with elaborate precision. In the former, besides other differences between male and female, the female is said to have the 'first foot' (or leg) bifurcate, while in the male it is undivided. It seems a trifling matter, but it is true; it is so small a point that I searched long before at last I found mention made of it in a German monograph. The puzzling thing is that it is (as we should say) the last and not the first leg which is so distinguished; but after all, it is only a convention of our own to count the limbs from before backwards. To inspect a lobster's limbs, we lay it on its back (as Aristotle did), and see the legs overlapping, each hinder one above the one before; the hindmost is the first we see, and the one we must first lift up to inspect the others.

Aristotle's account of fishes is a prodigious history of habits, food, migrations, modes of capture, times and ways of spawning, and anatomical details; but it is not here that we can elucidate or even illustrate this astonishing Ichthyology. It is not always easy to understand--but the obstacle lies often, I take it, in our own ignorance. The identification of species is not always plain, for here as elsewhere Aristotle did not reckon with a time or place where the familiar words of Greek should be unknown or their homely significance forgotten. Among the great host of fish-names there are several referring, somehow or other, to the Grey Mullet, which puzzle both naturalist and lexicographer. A young officer told me the other day how he had watched an Arab fisherman emptying out his creel of Grey Mullet on some Syrian beach, and the Arab gave four if not five names to as many different kinds, betwixt which my friend could see no difference whatsoever. Had my friend been an ichthyologist he would doubtless have noticed that one had eyelids and the others none; that one had little brushes on its lips, another a small but wide-open slit under the jaw, another a yellow spot on its gill-covers, and so on. The Mullets are a difficult group, but Aristotle, like the Arab fisherman, evidently recognized their fine distinctions and employed the appropriate names. Again, Aristotle speaks of a certain nest-building fish, the 'phycis', and regarding this Cuvier fell into error (where once upon a time I followed him). In Cuvier's time there was but one nest-building fish known such as to suit, apparently, the passage, namely the little black goby; but after Cuvier's day the nest-building habits of the 'wrasses' became known to naturalists, as they had doubtless been known ages before to the fishermen--and to Aristotle.

Like almost every other little point on which we happen to touch, we might make this one the starting-point (here comes in the delight and fascination of the interpreter's task!) for other stories.

Speusippus, Plato's successor in the Academy, was both philosopher and naturalist, and we may take it, if we please, that his leaning towards biology, and the biological trend which at this time became more and more marked in Athenian philosophy, were not unconnected with the great impulse which Aristotle had given. However this may be, Speusippus wrote a book περι Ὁμοιων {peri Homoiôn} 'Concerning Resemblances'; and this, of which we only possess a few fragmentary sentences, must have been a very curious and an interesting book. He mentions, among other similar cases, that our little fish _phycis_ has a close outward semblance to the sea-perch; and this is enough to clinch the proof that Aristotle's nest-building fish was not a goby but a wrasse. The whole purport of Speusippus's book seems to have been to discuss how, or why, with all Nature's apparently infinite variety, certain animals have a singularly close resemblance to certain others, though they be quite distinct in kind. It is a problem which perplexes us still, when we are astonished and even deluded by the likeness between a wasp and a hover-fly, a merlin and a cuckoo. In certain extreme cases we call it 'mimicry', and invoke hypotheses to account for this 'mimetic' resemblance; and those of us who reject these hypotheses must fain take refuge in others, as far-reaching in their way. This at least we know, that Speusippus seized upon a real problem of biology, of lasting interest and even of fundamental importance.

To come back to Aristotle and his fishes, let us glance at one little point more. The reproduction of the eel is an ancient puzzle, which has found its full solution only in our own day. While the salmon, for instance, comes up the river to breed and goes down again to the sea, the eel goes down to the ocean to spawn, and the old eels come back no more but perish in the great waters. The eel's egg develops into a little flattened, transparent fish, altogether different in outward appearance from an eel, which turns afterwards into a young eel or 'elver'; and Professor Grassi, who had a big share in elucidating the whole matter, tells us the curious fact that he found the Sicilian fishermen well acquainted with the little transparent larva (the _Leptocephalus_ of modern naturalists), that they knew well what it was, and that they had a name for it--_Casentula_. Now Aristotle, in a passage which I think has been much misunderstood (and which we must admit to be in part erroneous), tells us that the eel develops from what he calls γης εντερα {gês entera}, a word which we translate, literally, the 'guts of the earth', and which commentators interpret as 'earthworms'! But in Sicilian Doric, γης εντερα {gês entera} would at once become γας εντερα {gas entera}; and between 'Gasentera' and the modern Sicilian 'Casentula' there is scarce a hairbreadth's difference. So we may be permitted to suppose that here again Aristotle was singularly and accurately informed; and that he knew by sight and name the little larva of the eel, whose discovery and identification is one of the modest triumphs of recent investigation.

Aristotle's many pages on fishes are delightful reading. The anatomist may read of such recondite matters as the _placenta vitellina_ of the smooth dog-fish, whereby the viviparous embryo is nourished within the womb, after a fashion analogous to that of mammalian embryology--a phenomenon brought to light anew by Johannes Müller, and which excited him to enthusiastic admiration of Aristotle's minute and faithful anatomy. Again we may read of the periodic migration of the tunnies, of the great net or 'madrague' in which they are captured, and of the watchmen, the θυννοσκοποι {thynnoskopoi}, the 'hooers' of our ancient Cornish fishery, who give warning from tower or headland of the approaching shoal. The student may learn what manner of fish it was (the great Eagle-ray) with whose barbed fin-spine--most primitive of spear-heads--Ulysses was slain; and again, he may learn not a little about that ναρκη {narkê}, or torpedo, to which Meno compared his master Socrates, in a somewhat ambiguous compliment.

In rambling fashion Aristotle has a deal to tell us about insects, and he has left us a sort of treatise on the whole natural history of the bee. He knew the several inmates of the hive, though like others of his day (save, perhaps, only Xenophon), and like Shakespeare too, he took the queen-bee for a king. He describes the building of the comb, the laying of the eggs, the provision of the larvae with food. He discusses the various qualities of honey and the flowers from which these are drawn. He is learned in the diseases and the enemies of bees. He tells us many curious things about the economy of the hive and the arts of the bee-keeper, some of which things have a very modern and familiar look about them: for instance, the use of a net or screen to keep out the drones, a net so nicely contrived that these sturdy fellows are just kept out, while the leaner, slenderer workers are just let in. But it would be a long, long story to tell of Aristotle's knowledge of the bee, and to compare it with what is, haply, the still deeper skill and learning of that master of bee-craft, Virgil.

Then, having perfect freedom to go whithersoever we chose and to follow the bees across the boundless fields of ancient literature, we might read of the wild bees and of their honey out of a rock, and of the hive-bees too, in Homer; follow them to their first legendary home in Crete, where the infant Jupiter was fed on honey--as a baby's lips are touched with it even unto this day; trace their association with Proserpine and her mother, or their subtler connexion with Ephesian Diana; find in the poets, from Hesiod to the later Anthology, a hundred sweet references--to the bee-tree in the oak-wood, to the flowery hill Hymettus. Perhaps, at last, we might even happen on the place where Origen seems so strangely to foreshadow Shakespeare--speaking of the king of the bees with his retinue of courtiers (his officers of sorts), the relays of workmen (the poor mechanic porters crowding in), the punishment of the idle (where some, like magistrates, correct at home), the wars, the vanquished, and the plunder (which pillage they with merry march bring home To the tent-royal of their Emperor).

Go back to Aristotle, and we may listen to him again while he talks of many other kindred insects: of the humble-bee and its kind, of the mason-bee with its hard round nest of clay, of the robber-bees, and of the various wasps and hornets; or (still more curiously and unexpectedly) of the hunter-wasp or 'ichneumon', and how it kills the spider, carries it home to its nest, and lays its eggs in its poor body, that the little wasp-grubs may afterwards be fed. Or again of the great wasps which he calls Anthrenae, and how they chase the big flies, and cut off their heads, and fly away with the rest of the carcass--all agreeing to the very letter with what Henri Fabre tells us of a certain large wasp of Southern Europe, and how it captures the big 'taons' or horse-flies: 'Pour donner le coup de grâce à leurs Taons mal sacrifiés, et se débattants encore entre les pattes du ravisseur, j'ai vu des Bembex mâchonner la tête et le thorax des victimes.' Verily, there is nothing new under the sun.

With the metamorphoses of various insects Aristotle was well acquainted. He knew how the house-fly passes its early stages in a dung-hill, and how the grubs of the big horse-flies and Tabanids live in decayed wood; how certain little flies or gnats are engendered (as he calls it) in the slime of vinegar. He relates with great care and accuracy the life-history of the common gnat, from its aquatic larva, the little red 'blood-worm' of our pools; he describes them wriggling about like tiny bits of red weed, in the water of some half-empty well; and he explains, finally, the change by which they become stiff and motionless and hard, until a husk breaks away and the little gnat is seen sitting upon it; and by and by the sun's heat or a puff of wind starts it off, and away it flies.

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 {psychê}, the Soul. They had a curious name (νεκυδαλλος {nekydallos}) for the pupa. It sounds like a 'little corpse' (νεκυς {nekys}); 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