But what are these to the array of qualities that Leonardo possessed? I will try to arrange them as best I can in order. Under some headings I shall give only a few facts, but they will be of such a kind as to imply that he was well versed in the subject in question.

Painter: We have already said enough.

Sculptor: He was second only to Michael Angelo, and had not the Gascon archers of Louis XII destroyed his famous equestrian statue, he might have led Michael Angelo a tight race for the laurel crown of the Christian era. In preparation for this statue he made a study of the anatomy of the horse, and wrote a treatise thereon which was a standard on the subject.

Architect: He collaborated with Bramante (the architect of St. Peter's), and, in 1487, we find him at work on the Milan Cathedral. These two facts are full of significance.

Poet and Orator: Only half a dozen of his rhymed lines have come down to us, but in his History of Painting he is always talking of poetry in connexion with painting, so it is likely he had the poetic gift. Also in this same treatise he gives, in prose however, descriptions of nature, especially in savage mood, that contain the very essence of poetry, and are worthy of Virgil. Also a description of battles, which probably was written in connexion with his 'Battle of the Standard.' As an orator he had a great gift, we are told, and fascinated all who came within his influence.

Musician: We do not say that he was one of the great composers, but it was in that capacity (also as inventor of machines of war) that he first came to Milan. Vasari says he was the greatest improvisatore of his age. He sang with a voice of great charm, composed his own words, set them to music, and played on instruments made with his own hands, notably on a silver one in shape like a horse's head-thus made to give greater sweetness of tone. He was also employed by Ludivico Sforza as the master of pageants, and always contrived to have something striking and original.

Mathematician: He helped the great mathematician, Luca Pacioli, in his treatise De divina proportione. Specimens of his work may be seen, in desultory fashion, in the drawings at the Windsor Library. It may be of interest to say in passing that he is credited with the authorship of the symbols + and -. He was the founder of mathematical physics (see under Physicist).

Astronomer: He anticipated Copernicus in propounding the theory of the earth's movement. He gives his reasons, on which we need not dwell; it is sufficient for our purpose to note his categorical statement that the sun does not move: Il sole non si move.1 He had a presentiment of the telescope when he wrote: 'It would be possible to invent a glass that would bring the moon nearer.' He explained the obscure light on the unilluminated part of the moon. He made a deep study of tides, and even wrote to correspondents to report to him the state of the tides in the Caspian and Black Seas. Also he knew of the gathering of equatorial above the polar waters. And, we might interject here, he worked out a theory of the motion of the waves. Other facts could be adduced, but these will suffice.

Geologist: In geology his reasoned speculations were as daring as they have since been proved accurate. With keen, scientific intuition, he concluded that the earth was not always as we see it; that, in fact, it has had a history or a past.' And so he created the science of Stratigraphy (the order and relative position of strata), and taught the lesson to be learned from fossils. He anticipated Cuvier by some three hundred years in saying that the bed of the ocean is ever changing. Briefly he reasoned thus: Whence came the sea-shells found on tops of mountains? Not from the Deluge (as was popularly supposed); nor could the mollusca have climbed thither. Therefore, the sea must once have covered those mountains. But why the change? It is due to the erosion of the sea, as a result of which the centre of gravity of the earth is ever changing, and as the earth swings round to keep its centre of gravity at its own centre, the sea is ever receding from its old floor and making itself a new one. He pointed out that the tributaries of the river Po at one time flowed into the Gulf, and he calculated that it took 200,000 years to effect the change-a daring statement because of the then traditional view regarding the age of the world. While at Cairo he noticed the formation of the Nile valley, and said the day would come when the Nile would make tributaries of all rivers flowing into the Mediterranean, and would itself discharge its waters at Gibraltar. He also explained the origin of mountain lakes, instancing those of Garda and Maggiore, as due to the

1 Müntz: Leonardo da Vinci.

breaking down of mountains. More might be said, but this is, perhaps, enough.

Biologist: A few examples will suffice to prove that he took no mere passing interest in the subject. He said that motion is the cause of all life: Il moto è causa d'ogni vita.1 He was the first to propose the division of animals into two great classes, those with skeletons inside, and those with skeletons outside, such as cockles, oysters, etc., a division which practically corresponds with the vertebrates and invertebrates of Lamark. He distinguished between the movements which are dependent on the brain, and those which are due to the immediate effect of the spinal marrow on the functions of the nervous system. The examples of the latter which he gives are epileptics, and the tails of lizards when cut off. In speaking of growth, he makes a statement which I quote for what it is worth (I don't know if it is true), that children at the age of three are, as a rule, half the height they will ultimately attain.

2

Anatomist: In anatomy he did astonishing work. We have seen it stated that he studied anatomy with the famous Marco della Torre, Professor at Padua and Pavia. But this is understating the case. He was an anatomist when the latter was only seven years of age; he first got him interested in the work, and was his master. He admitted to one of the Cardinals at Rome that he dissected several corpses of men, women, and children; and we are told that he shared his home with corpses flayed, stripped of flesh and terrible to look at.'' He then made sketches for the use of students who might not have courage or time to go directly to the real corpse. These sketches may still be seen in the Windsor Library. Duval (in work mentioned in note) devotes much attention and admiration to him, and tells us that Leonardo intended writing a treatise on anatomy, beginning with the skeleton, then dressing it with muscles, nerves, blood-vessels and cartilages, and ending with the skin. He even collates his notes and divides them into three divisions. Da Vinci divined the circulation of the blood, but missed the explanation of its mechanism. Here are his words: The heart is a muscle of great strength, much stronger than the other

1 Richter, vol. ii. p. 286

2 v.g., Woltmann and Woermann: Hist. of Painting, vol. ii. p. 461. 3 Duval : L'Anatomie des Maitres, p. 13.

muscles. The blood which returns when the heart opens again is not the same as that which closes its valves.' It may be objected that the ancients knew of the circulation. Yes, as air in a chamber. The important statement in the foregoing is that the heart is a muscle. Some seventy years after this was written, Realdo Columbus formally denied the muscularity of the heart, although his is one of the big names in the history of anatomy.'

1

Botanist To put it briefly, he knew every important discovery since made in botany with the single exception of the sex of plants. For instance: he was the first to lay down the laws that govern the disposal and arrangement of leaves about their stalks. An Englishman named Brown got credit for this in 1658-that was about one hundred and seventy years after Da Vinci. He explained the growth of bark; also he knew that rings correspond with age in trees, noting that the rings varied with humidity or dryness of season; likewise that they showed the orientation of the tree, for they are wider and thicker on the north side than on the south, so that the cone of the trunk is nearer to the bark on the south than on the north.' And

so on.

6

Engineer: Here we come to the subject he loved most. He constructed the famous Martesana Canal, and linked Milan with the rivers and great lakes, and irrigated the entire Lombard plain, so that the fertility for which it is famous to-day is due to him. For seven years (1480–1487) he was employed on engineering works by the Sultan of Cairo.3 In passing we might remark that during his stay in the Orient he is said to have mastered all its secret lore, and ever afterwards wore the peculiar turban that is so familiar to us in the portrait painted by himself. The great weight of authority says he was the first inventor of canal locks. Certain it is the invention was purely original on his part, and equally certain that our present system of locks is all his. Even before he gave his invention to the world, he used to surprise his friends, in the mysterious manner so peculiar to him, by saying: 'I can make boats

1 De Re Anatomica, 1559.

2 See Encyc. Britt., under 'Harvey.'

This Sultan seemed to welcome the genius of Italy, for Michael Angelo once decided to give his services to him, having left Rome in a fit of temper. But Pope Julius II sent messengers after him with orders that they were to bring him back by force if necessary.

VOL XIV-20

sail over hills.' It is rather interesting, as showing the versatility of the man, that, when the Duchess Isabella Gonzaga wrote to him begging for a painting, at least for a small Madonna, devout and sweet,' he kept putting her off, because he was busy at the time preventing a landslide on a neighbouring hill, on canalizing and controlling the waters of the Arno, and on working out his investigations about tides. During his final years in France he had on hands a gigantic scheme for rendering the Loire navigable, and for linking it by a canal with the Saône.

As we have touched on his travels, we might here remark that he was also an explorer, and invariably made maps of all places he passed through.

Physicist : Alexander Von Humboldt says: 'He was the greatest physicist of the fifteenth century, uniting a remarkable knowledge of mathematics with a most admirable intuition of nature'; and he goes on to say: 'Like Bacon, and a century earlier, Leonardo held induction for the only sure method in the natural sciences.' Windelband,1 in criticizing Bacon for not attaching due importance to mathematics, says: His tendency towards the practical end of invention blinded Bacon to the theoretical value of mathematics. . . . Modern investigation was born of empirical Pythagoreanism (in simpler words, mathematical physics). This problem had been seen already by Leonardo da Vinci.' (Italics mine.)

He touched on gravity, equilibrium, compressibility, elasticity, dilatation, radiation of heat, fusion, magnetism, and friction. He discovered the law of the composition of concurrent forces; determined the centre of gravity of the tetrahedron; anticipated Pascal's hydrostatic law; knew the law of equilibrium of two liquids of different density in communicating tubes; had knowledge of the law of conservation of energy; arrived at correct conclusions concerning the impossibility of perpetual motion; asserted that the velocity of a body that falls freely is proportional to the time occupied in the fall, and showed how this applies also to an inclined plane. He was much engrossed in the elastic reactions that cause bodies to rebound after they strike other bodies; and in this connexion he was the first to give a true explanation of the flight of birds. Up to his time their flight was regarded as a problem in statics, and

1 History of Phil., p. 387.