Leonardo, whose birth antedates that of Michelangelo and Raphael by
twenty three and thirty-one years respectively, was thus in the
forefront of the Florentine Renaissance, his life coinciding almost
exactly with the best period of Tuscan painting.
Leonardo was the first to investigate scientifically and to apply to
art the laws of light and shade, though the preliminary investigations
of Piero della Francesca deserve to be recorded.
He observed with strict accuracy the subtleties of chiaroscuro--light
and shade apart from colour; but, as one critic has pointed out, his
gift of chiaroscuro cost the colour-life of many a noble picture.
Leonardo was "a tonist, not a colourist," before whom the whole book
of nature lay open.
It was not instability of character but versatility of mind which
caused him to undertake many things that having commenced he
afterwards abandoned, and the probability is that as soon as he saw
exactly how he could solve any difficulty which presented itself, he
put on one side the merely perfunctory execution of such a task.
In the Forster collection in the Victoria and Albert museum three of
Leonardo's note-books with sketches are preserved, and it is stated
that it was his practice to carry about with him, attached to his
girdle, a little book for making sketches. They prove that he was
left-handed and wrote from right to left.