He then applied himself, but with greater care, to the anatomy of man, assisted by and in turn assisting, in this research, Messer Marc' Antonio della Torre, an excellent philosopher, who was then lecturing at Pavia, and who wrote of this matter; and he was one of the first (as I have heard tell) that began to illustrate the problems of medicine with the doctrine of Galen, and to throw true light on anatomy, which up to that time had been wrapped in the thick and gross darkness of ignorance. And in this he found marvellous aid in the brain, work, and hand of Leonardo, who made a book drawn in red chalk, and annotated with the pen, of the bodies that he dissected with his own hand, and drew with the greatest diligence; wherein he showed all the frame of the bones; and then added to them, in order, all the nerves, and covered them with muscles; the first attached to the bone, the second that hold the body firm, and the third that move it; and beside them, part by part, he wrote in letters of an ill-shaped character, which he made with the left hand, backwards; and whoever is not practised in reading them cannot understand them, since they are not to be read save with a mirror. Of these papers on the anatomy of man, a great part is in the hands of Messer Francesco da Melzo, a gentleman of Milan, who in the time of Leonardo was a very beautiful boy, and much beloved by him, and now is a no less beautiful and gentle old man; and he holds them dear, and keeps such papers together as if they were relics, in company with the portrait of Leonardo of happy memory; and to all who read these writings, it seems impossible that that divine spirit should have discoursed so well of art, and of the muscles, nerves, and veins, and with such diligence of everything. So, also, there are in the hands of ----,[11] a painter of Milan, certain writings of Leonardo, likewise in characters written with the left hand, backwards, which treat of painting, and of the methods of drawing and colouring. This man, not long ago, came to Florence to see me, wishing to print this work, and he took it to Rome, in order to put it into effect; but I do not know what may afterwards have become of it. And to return to the works of Leonardo; there came to Milan, in his time, the King of France, wherefore Leonardo being asked to devise some bizarre thing, made a lion which walked several steps and then opened its breast, and showed it full of lilies. In Milan he took for his assistant the Milanese Salai, who was most comely in grace and beauty, having fine locks, curling in ringlets, in which Leonardo greatly delighted; and he taught him many things of art; and certain works in Milan, which are said to be by Salai, were retouched by Leonardo.