What counts, certainly, for much of what is so extraordinary in the genius of Leonardo da Vinci--who died exactly five hundred years ago--is the fact that the noble blood he inherited (the so-called dishonor that hangs over his birth being in his case a singular honor) is curiously like the stain of some strange color in one of his paintings; he being the least of all men to whom there could be anything poisonous in the exotic flowers of evil that germinated in Milan; where, as in Venice and in Rome, moved a changeful people who, in the very midst of their exquisite and cruel amusements, committed the most impossibly delicious sins, and without the slightest stings of conscience. Savonarola, from whom, in the last years of his life, Botticelli caught the contagion of the monk's fanaticism, was then endeavoring to strip off one lovely veil after another from the beauty of mortal things, rending them angrily; for which, finally, he received the baptism of fire. Rodrigo Borgia--a Spaniard born in Xàtiva--then Pope Alexander VI, was fortunate enough to possess in his son, Cesare, a man of sinister genius--cruel, passionate, ardent--who had the wonderful luck of persuading Leonardo to wander with him in their wild journey over Central Italy in 1502, as his chief engineer, and as inspector of strongholds. Not even the living pages of Machiavelli can give us more than a glimpse of what those conversations between two such flame-like creatures must have been; yet, we are aware of Cesare being condemned by an evil fate, as evil as Nero's, to be slain at the age of thirty-one, and of Leonardo, guided by his good genius, living to the age of sixty-seven.
The science of the Renaissance was divided, as it were, by a thousand refractions of things seen and unseen; so that when Leonardo, poring over his crucibles, desires no alchemist's achievement, but the achievement of the impossible, his vision is concentrated into infinite experiences, known solely to himself; exactly as when, in his retirement in the villa of the Melzi, his imagination is stirred feverishly as he writes detached notes, as he dashes off rapid drawings; and always not for other men's pleasure, but simply for his own; careless, as I think few men of genius have ever been, of anything but the moment's work, the instant's inspiration. And, what is also certain is that Da Vinci like Shakespeare created, ambiguously for all the rest of the world, flesh that is flesh and not flesh, bodies that are bodies and not bodies, by something inexplicable in their genius; something nervous, magnetic, overwhelming; and, to such an extent, that if one chooses to call to mind the greatest men of genius who have existed, this painter and this dramatist must take their places beside Aeschylus and beside Balzac.