The following passages from Vasari's and Condivi's Lives deserve attention by those who approach the study of Buonarroti's drawings. Vasari says: "His powers of imagination were such, that he was frequently compelled to abandon his purpose, because he could not express by the hand those grand and sublime ideas which he had conceived in his mind; nay, he has spoiled and destroyed many works for this cause; and I know, too, that some short time before his death he burnt a large number of his designs, sketches, and cartoons, that none might see the labours he had endured, and the trials to which he had subjected his spirit, in his resolve not to fall short of perfection. I have myself secured some drawings by his hand, which were found in Florence, and are now in my book of designs, and these, although they give evidence of his great genius, yet prove also that the hammer of Vulcan was necessary to bring Minerva from the head of Jupiter. He would construct an ideal shape out of nine, ten and even twelve different heads, for no other purpose than to obtain a certain grace of harmony and composition which is not to be found in the natural form, and would say that the artist must have his measuring tools, not in the hand, but in the eye, because the hands do but operate, it is the eye that judges; he pursued the same idea in architecture also." Condivi adds some information regarding his extraordinary fecundity and variety of invention: "He was gifted with a most tenacious memory, the power of which was such that, though he painted so many thousands of figures, as any one can see, he never made one exactly like another or posed in the same attitude. Indeed, I have heard him say that he never draws a line without remembering whether he has drawn it before; erasing any repetition, when the design was meant to be exposed to public view. His force of imagination is also most extraordinary. This has been the chief reason why he was never quite satisfied with his own work, and always depreciated its quality, esteeming that his hand failed to attain the idea which he had formed within his brain." XI