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Leonardo, of course, took precautions to guard against the theft of his discoveries, and so was not over-anxious to communicate the fruits of his own toil. Only a foolish inventor would do otherwise. But take the terms esoteric and hermetic in their common meaning, as characterising the initiation into certain practices which are only handed down through a very small number of pupils, and under the seal of secrecy; it is then clear that the whole practice of the founder of the Milanese Academy was inconsistent with any approval of methods so contrary to the scientific spirit. No doubt, as the Marchese d'Adda has told us, he manipulated crucibles and alembics, distilled perfumes and purified oils, prepared pigments, varnishes and acids, composed mixtures for fire-works or deleterious fumes, but he never failed to set his face against everything esoteric. Thus we find him inveighing against the alchemists: “ The new interpreters of nature declare that quicksilver is a seed common to all metals; they forget that Nature varies seed according to the differences in the matters it wishes to produce.”
Elsewhere he cries out against chiromancy and necromancy. In denying the value of chiromancy, he has even shown himself more clear-sighted than Aristotle, to say nothing of those modern professors of the science who fill our drawing-rooms. The Greek philosopher, after asking why people with a line stretching from one end to the other of the palm have the best chance of long life, does not hesitate to answer that beings without articulations have little vitality. Now, he adds, it is, above all, those beings whose nature it is to be without articulation, and who are yet articulated, who live the longest. What does Leonardo say ? “Talking of predicting the future by the lines on the hand, it is certain that great armies and numerous crews of ships have met death at the same moment, and in the same way, in battle or shipwreck, and yet that no two victims had similar signs on their hands.” What argument could be sounder ?
Then he attacks the seekers after perpetual motion. “Oh! speculators on perpetual motion, how many vain projects of the like character you have formed! Go and consort with the searchers after gold.” 1 Problems, section xxxiv., § 10; cf. section x., $ 40.
Or again, “Many have made a trade of delusions and false miracles, deceiving the stupid multitude.” Farther on, “Among all human opinions, we must consider as the stupidest the belief in necromancy, the sister of alchemy, which pretends to create simple and natural things.” Next he asks whether the spirit is able to speak or not, and answers his own question with arguments worthy of a modern positivist.1 In short, it is safe to assert that views so deep and broad have never been allied with such powers of minute observation. No savant of his time pronounced himself so categorically as Leonardo against all false doctrine. His “magic ” consisted in digging more deeply, and with more independence than any one else had shown, into the mysteries of Nature. His curiosity drew him, no doubt, towards the sciences which were called occult, but the incomparable rectitude of his judgment kept him from being in any way their dupe. He loved to play with fire, but he took good care that his fingers remained intact. What a loss that has been for the mystics and for painters! With his high, deeply furrowed brow, his thick eyebrows, his sarcastic smile, his long untrimmed beard, he would have been a fine figure in a picture, surrounded by a magic circle, wand in hand, raising the dead and deflecting the course of the stars ! 2
“Reality, with its cold definitions, its vague and unexplored horizons, and its narrow limits, could not satisfy,” as an eloquent and learned writer recently put it to me,3 " the ardent spirit of research which made both the greatness and the torment of Leonardo. Dawning science, with its dimly seen wonders, art itself, with its foretaste of immortality, could not fill his restless soul. Nature remained. Like an enchanted forest, concealing dazzling treasures in its depths, nature surrounded him, but continually escaped his grasp. Before he could seize her secrets, he had first to borrow her methods, to imitate her behaviour, to keep off by various devices the profane curiosity of man. Hence the fanciful sides of his conduct, the trouble he took to make his writing indecipherable. His early taste for such things as the Medusa's head, and the painting or actual imitation of other monsters calculated to frighten those about him, were no more than the relaxations of a superior mind, amusing itself with the childish ideas of the simple and comparatively primitive intelligences about it."
i See Richter, vol. ii., p. 301-308.
2 Has any one ever called attention to the curious likeness between Leonardo and Darwin ? Their facial characteristics were almost identical [Ed.]
3 Madame Raffalovitch.
We should measure Leonardo with his contemporaries if we wish to understand how far in advance of his time he was. The illustrious old man had scarcely yielded his last breath in his voluntary exile at Amboise, before the occult sciences were again getting the upper hand all over Europe. Cardan, Paracelsus, Campanella, were “adepts," "magians,” “occult
(Sabachnikoff Collection.) ists,” in the sense which we now use those words; they had a right to 'pose as the heirs of Hermes Trismegistus, of Pythagoras, and of Apollonius ; for the same reason they were forerunners of the SaintGermains and Cagliostros, and of those magians of our own “ fin-de-siècle," who have, at least, this one advantage over their predecessors, that they are perfectly honest in their absurdities.
We must confess that at the first glance the labours of Cardan seem more systematic, more synthetic, and better co-ordinated than those of his rival; to the strokes of genius of the latter, he opposes a perfectly organic whole. But how often his laborious erections are unsound in their foundations; how often, in his long chains of
STUDIES OF THE FLIGHT OF BIRDS.
reasoning, does he not turn in a vicious circle! He believes in the influence of the stars, and dwells upon childish comparisons ; while, on the other hand, Leonardo never fails to compel our respect by the gravity of his ideas, and the luminous fertility of his generalisations.
Cardan's credulity may be judged from a few instances: he declares, on the authority of Albertus Magnus, that the sapphire cures anthrax by simple contact ; he asserts that every precious stone possesses some hidden virtue; that the tooth of the badger or the left foot of the same animal, if attached to the right arm, strengthens the memory. Silver and gold, he asserts, are contained in all the other metals, &c.
In attempting an analysis of those wonderful scientific researches which would have sufficed to immortalise Leonardo, even if he had never painted either the Last Supper or the Mona Lisa, there are two rocks of which we must be careful to steer clear : on the one hand we must not take every "obiter dictum” too much in earnest, on the other we must not forget the relations, direct or indirect, of the master with his predecessors. A fame like his does not require to be enhanced by the credit which belongs to others.
To give an example : Leonardo says somewhere that he wishes some one would make a glass to magnify the moon, whereupon his biographers claim for him the credit of having invented the telescope !
In his note-books he often mixes up his own observations with those of others. Has not the treatise on the fabled virtues of animals, the text of which has been preserved in his manuscripts, been attributed to him, whereas we know that all he had to do with it was to waste his time in copying out a mass of superstitious nonsense at which he must have been the first to laugh. I do not hesitate to say that in all these matters everything has yet to be done. Without a methodical examination of what his predecessors have left, it is impossible to do justice to Leonardo's share in building up that edifice of modern science which has required the energies of so many generations of workers.
In the domain of mathematics, Leonardo turned his attention successively to geometry, mechanics, and astronomy. The reader will understand that here I must be content with a few illustrations, leaving to specialists the task of setting this part of the master's activity in a full light.
In the field of pure mathematics, Leonardo's writings seem to have less novelty than elsewhere. He is credited, but without any decisive evidence, with the invention of the two symbols + and -, He studied equations, too, as we may judge from one of his memoranda, but we do not know how far he advanced in that direction.
As for geometry, Libri's assertion that he declared the squaring of the circle to be impossible is open to doubt.1
Gliding—and for good reason !-over the geometrical and astronomical studies of da Vinci, let me endeavour to do justice to some of the discoveries with which he enriched the mechanical and physical sciences, discoveries, indeed, which were platonic enough, seeing that they remained so long unpublished.
Leonardo called mechanics the Paradise of the Sciences. For no other branch of mathematics did he feel the same passion as for this ; no other left so many traces in his writings and among his drawings. Mechanics, in his eyes, embraced and included every manifestation of force and movement, aërial locomotion, motion in water, the action of gunpowder, and that of the innumerable machines over which he lavished his ingenuity, &c. A few quotations will suffice to show the character of his thoughts on this subject. His definition of force is in every way worthy of an antique philosopher or of a modern savant : “Force is a spiritual power without force and impalpable, which manifests itself for a short time in bodies deprived of their natural repose by some accidental violence. I call it spiritual, because the life in it is invisible and without body; impalpable, because the body in which it is produced is increased neither in size nor in weight."
Leonardo anticipated Copernicus in propounding the theory of the
i Govi, Saggio, p. 13.-Rudio, Ueber den Antheil der mathematischen Wissenschaften an der Kultur der Renaissance, Hamburg, 1892, p. 20-23.