There was nothing, he said--for he spoke willingly to any one who questioned him on these subjects--more beautiful than the manner in which human beings are built, or indeed living creatures of any kind; for, in the scarcity of corpses and skeletons, he would pick up on his walks the bones of sheep that had died on the hill-sides, or those of horses and mules furbished up by the scavenger dogs of the river-edge. It was marvellous to listen to him when he was in the vein. He sat handling horrible remains and talking about them like a lover about his mistress or a preacher about God; indeed, bones, muscles, and tendons were mistress and god all in one to this fanatical lover of human form. He would insist on the loveliness of line of the scapula, finding in the sweep of the _acromion_ ridge a fanciful resemblance to the pinion, and in the angular shape of the _coracoid_ process to the neck and head of a raven in full flight. Following with his finger the triangular outline of the bone, he went on to explain how its freedom of movement is due to its singular independence; laid loosely on the flat muscles behind the upper ribs, it moves with absolute freedom, backwards and forwards, up and down, unconnected with any other bone, till, turning the corner of the shoulder, it is hinged rather than tied to the collar-bone; the collar-bone itself free to move upwards from its articulation in the sternum. And then talk of the great works of man! Talk of Brunellesco and his cupola, of the engineers of the Duke of Calabria! Look at the human arm: what engineer would have dared to fasten anything to such a movable base as that? Yet an arm can swing round like a windmill, and lift weights like the stoutest crane without being wrenched out of its sockets, because the muscles act as pulleys in four different directions. And see, under the big _deltoid_, which fits round the shoulder like an epaulette and pulls the arm up, is the scapular group, things like tidily sorted skeins, thick on the shoulder-blades, diminished to a tendon string at their insertion in the arm; their business is to pull the arm back, in opposition to the big pectoral muscle which pulls it forwards. Here you have your arm working up, backwards or forwards; but how about pulling it down? An exquisite little arrangement settles that. Instead of being inserted with the rest on the outside of the arm-bone, the lowest muscle takes another road, and is inserted in the under part of the bone, in company with the great _latissimus dorsi_, and these tightening while the _deltoid_ slackens, pull the arm down. No other arrangement could have done it with so little bulk; and an additional muscle on the under-arm or the ribs would have spoilt the figure of Apollo himself.