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1489, that is to say, when Torre was only seven years old. Leonardo seems to have continued his researches after his return to Florence. When he received the visit of the Cardinal d'Aragon in 1516, Leonardo boasted of having made dissections (“ haver facta natomia”) on more than a hundred subjects of all ages, some male and some female. The Anonimo (edited by Milanesi) adds that his studies were carried on in the hospital of Santa Maria Novella, at Florence.1
We have been told by an expert that Leonardo's anatomical studies were, unlike those of Michelangelo, directed less towards the study of the muscles, than to the observation of the effects produced upon our organs by the mind and the passions. In reproducing one of his anatomical drawings, M. Mathias Duval points out the almost overscrupulous care with which the master sets out to distinguish, by dissection, the different groups of the pectoral, the deltoid, and the sterno-mastoid muscles. We must remember, he adds, that Leonardo consecrates numerous chapters in the Trattato della Pittura to the description of the muscles of the body, of the joints of the limbs, of “the sinews and tendons which gather themselves up when such and such a muscle swells in order to produce such and such an action.” 2
In what he says about growth, we may note the interesting remark that at the age of three years people have reached one half of what is to be their final height. 3 According to my learned colleague, M. Edmond Perrier, this rule is fairly exact.
In the excess of his scientific probity, Leonardo nursed certain prejudices against the practice of medicine. Like some distinguished men of later times, he would have readily declared it to be rather an art than a science. His uncertain humour in this direction breaks out more than once. At one time we find him comparing doctors to alchemists; at another he declares that any one who takes medicines takes evil
1 We know that in 1506 the doctors of Florence obtained the corpse of a man who had been executed “per fare una notomia” (Landucci, Diario fiorentino, p. 273).
2 Précis d'Anatomie artistique, p. 15. 3 Richter, vol. i. p. 169.
advice. His rule of health is thus expressed : “Do not eat without appetite; restrict yourself to well cooked and simply prepared food, and masticate thoroughly.” Once, however, he confesses that “if illness is a want of harmony between the elements infused into the living body, medicine is the re-establishing of good relations between those elements.” 1
In his multitudinous researches Leonardo touches for a moment on ethnography. He asks himself why the inhabitants of hot countries are black, and he arrives at this somewhat fantastic explanation : Men born in hot countries love the night because it refreshes them, and hold the light in horror because it burns them ; this is why they have the colour of night, which is black. In cold countries we have a contrary result ! 2
Botany owes a few of its cardinal laws to Leonardo.
The combined studies of Messrs. Uzielli and Ravaisson-Mollien3 have proved that Leonardo was familiar with the writings of Theophrastus, some of whose experiments he mentions and even renews. Although he does not seem to have recognised the existence of sex in plants, he has at least enriched the science of botany with a large number of valuable observations. The system on which leaves are disposed and arranged about their stalks was the object of much patient study, as we see more particularly in the fourth book of the Trattato. He was the first to lay down the laws which govern this branch of science, and deserves the credit so long accorded to the Englishman, Brown, whose work did not appear until 1658.
Leonardo points out that the part of a tree's circumference which faces south shows more vigour and youth than the part which faces north. The rings in a section through the trunk or branches show the number of years they have existed, and the width of those rings corresponds to the humidity or dryness of the various years. They show, too, the orientation of the tree, for they are wider and thicker
i Richter, vol. ii. p. 133. 2 Richter, vol. ii. p. 270.
3 Conjectures à propos d'un Buste en Marbre de Béatrix d'Este. (Gazette des Beaux Arts, 1877, and Ricerche, vol. ii. p. 1–25.)
on the north side than on the south, so that the core of the trunk is nearer to the bark on the south side than on the north.1
In another passage Leonardo explains the growth of bark as follows: The increase in girth of plants is caused by the sap which develops in the month of April between the wood of the tree and
its liber. The liber then changes into bark, and fresh fissures are formed in the bark, at the bottom of the fissures already existing.
Among his other botanical researches we may refer to his studies of the action of poison upon plants.2
He thus describes the nutrition of plants : “ The sun gives the spirit of life to plants, while the earth nourishes them with its moisture. With regard to this, I have already tried the experiment of leaving only a very small root to a pumpkin ; it brought to perfection all the fruit the plant could produce, which amounted to sixty pumpkins of the long kind. I patiently devoted my mind to consider this result, and I saw that the moisture of the night dews, penetrating abundantly into the points of attachment of the large leaves, nourished the plant with its children, or rather the eggs which had to produce the children. Every branch, every fruit pod, is born at the springing of the leaves, which acts as mother to it, conveying to it the rain water and the dew." 2
i Montaigne found an artisan at Pisa (1580-81) who had noticed that the rings were narrower on the north side of a tree than on the south. (Voyage, Ancona edition, p. 484-485.)
2 Libri, Histoire des Sciences Mathématiques, vol. iii. p. 225.
It is in geology, however, that Leonardo claims the largest tribute of admiration by the originality of his views and the boldness of his conjectures. No one before him had penetrated so deeply into the mysterious cataclysms of our globe. His hypotheses, veritable strokes of genius as they are, are directly related to those of Lyell and Darwin. He does not even condescend to discuss the Biblical tradition as to the date of the creation ; his estimates proceed by hundreds and thousands of centuries. Neither is he embarrassed by the most appalling ideas of distance. After assigning to the accumulations formed by the Po a duration of two hundred thousand years, he prophesies that all the rivers which now fall into the Mediterranean will end by being tributaries of the Nile,
i Ravaisson-Mollien, MS. G, fols. 32, 33.
and that the latter will have its mouth at the Straits of Gibraltar, just as the rivers which once fell into the gulf of the Po are now affluents of the Po itself.
Long before Bernard Palissy, who has hitherto been called the leader in all these studies, the learned Italian had fixed his attention upon the shells found upon the tops of mountains. He shows that their presence at such a situation had nothing to do with any universal deluge, and he sets out the bases of his belief with a logical incisiveness which is rare enough. These, in substance, are his arguments : these shells were not deposited by the Deluge, as is proved by the fact that they are all found at one level, while the summits of many mountains rise above that level ; otherwise, they ought to appear at the summits of these mountains, and not at a short distance from their bases. To suppose that these molluscs, accustomed to live at the edge of the sea, had come to these places during the Flood, we should have to believe that these very slowly moving animals had made their way from the borders of the Adriatic to Montferrat in Lombardy, a distance of 250 miles (thousands of cubits), during the forty days of rain which produced the Deluge. To those who assert that they were carried by the waves, Leonardo answers that shell-fish, having regard to their weight, could only travel at the bottom of the sea. “If you will not allow this,” adds
1 “A potter, who knew neither Latin nor Greek, was the first who dared to assert, towards the end of the sixteenth century and before all Paris and its learned men, that fossil shells were real shells deposited in remote periods of the world in the places where they were then being found ; and that animals, and especially fishes, had given to figured stones and rocks all their different markings. This was Bernard Palissy, a native of Saintorge, and one of those great physicists whom nature alone can produce. His ideas, however, have slept for nearly a hundred years, and the name of their author is almost forgotten.” (Fontenelle, Histoire de l'Académie, 1720.)—In Bouillet's Dictionaire universel des Sciences, des Lettres, et des Arts (edition of 1874, p. 759), we find it asserted that Bernard Palissy was the first to put forward a really true and just theory of geology! And thus is history written even in the second half of the nineteenth century! A comparison of Leonardo's text with that of Palissy proves to demonstration where the credit for priority in the discovery should be assigned.
2 Speaking of the petrified shells found on mountains, Palissy denies that they “were spread over the earth in the days of the Deluge. Wherefore I maintain," he says farther on, “that the fishes, found petrified in various quarries, were begotten in those places, while the rocks were nothing but water and mud, which were afterwards turned into rock with the said fishes, as you will understand presently when I come to speak of the rocks of the Ardennes.” (Euvres complètes, ed. Gap., p. 273-275.)