At this period of his life Michelangelo devoted himself to anatomy. He had a friend, the Prior of S. Spirito, for whom he carved a wooden crucifix of nearly life-size. This liberal-minded churchman put a room at his disposal, and allowed him to dissect dead bodies. Condivi tells us that the practice of anatomy was a passion with his master. "His prolonged habits of dissection injured his stomach to such an extent that he lost the power of eating or drinking to any profit. It is true, however, that he became so learned in this branch of knowledge that he has often entertained the idea of composing a work for sculptors and painters, which should treat exhaustively of all the movements of the human body, the external aspect of the limbs, the bones, and so forth, adding an ingenious discourse upon the truths discovered by him through the investigations of many years. He would have done this if he had not mistrusted his own power of treating such a subject with the dignity and style of a practised rhetorician. I know well that when he reads Albert Dürer's book, it seems to him of no great value; his own conception being so far fuller and more useful. Truth to tell, Dürer only treats of the measurements and varied aspects of the human form, making his figures straight as stakes; and, what is more important, he says nothing about the attitudes and gestures of the body. Inasmuch as Michelangelo is now advanced in years, and does not count on bringing his ideas to light through composition, he has disclosed to me his theories in their minutest details. He also began to discourse upon the same topic with Messer Realdo Colombo, an anatomist and surgeon of the highest eminence. For the furtherance of such studies this good friend of ours sent him the corpse of a Moor, a young man of incomparable beauty, and admirably adapted for our purpose. It was placed at S. Agata, where I dwelt and still dwell, as being a quarter removed from public observation. "On this corpse Michelangelo demonstrated to me many rare and abstruse things, which perhaps have never yet been fully understood, and all of which I noted down, hoping one day, by the help of some learned man, to give them to the public. Of Michelangelo's studies in anatomy we have one grim but interesting record in a pen-drawing by his hand at Oxford. A corpse is stretched upon a plank and trestles. Two men are bending over it with knives in their hands; and, for light to guide them in their labours, a candle is stuck into the belly of the subject."