By the time he had attained to the end of his _third septenary_, viz. to the twenty-first year of his age, he had found out many things which were of great use to him for the conveniences of life. He made himself clothes and shoes of the skins of wild beasts after he had dissected them for use. He made himself thread of their hair, as also of the rind of the stalks of althea mallows, and other plants that could be easily parted asunder and drawn into threads. And he learned the making of these threads from the use he had made of the rushes before. He made a sort of bodkin of the strongest thorns he could get and splinters of cane sharp pointed with stones. The art of building he was taught by the observations he made upon the swallows' nests. He built himself a room to repose and rest therein, and also a store-house and pantry to lay up the remainder of his victuals. He guarded it with a door made of canes twisted together to prevent any of the beasts from getting in when he happened to be away. He also got hold of certain birds of prey which he made use of for hawking, and others of the tamer sort which he bred up, and fed upon their eggs and chickens. He also took to him the horns of wild bulls, which he fastened upon the strongest canes he could get and the staves of the tree Alzan and others of similar kind. Thus, by the help of fire and of sharp edged stones, he so fitted them that they served him as spears. He made himself also a shield of the skins of beasts folded and compacted together. And thus he tried to provide himself with artificial weapons, being destitute of natural arms. _Hayy learns to ride._ When he saw that his hand supplied all those defects quite well, and that none of the various kinds of wild beasts ventured to stand up against him, but fled away from him and only excelled him in their swiftness, he bethought himself of contriving some art how to be even with them, and finally decided there would be nothing so convenient as to chase some of the strongest and swiftest beasts of the Island, nourishing them with food until they might let him get on the back of them, so that he might pursue other kinds of wild beasts. There were in that island wild horses and asses, out of which he chose some that seemed fittest for the purpose, and by dint of exercise he made them so tractable that he became complete master of his wishes. And when he had made out of the skins of those beasts something that served him instead of bridles and saddles, it was an easy matter for him to overtake such beasts, which he scarcely could have taken in any other way. He made all these discoveries whilst he busied himself in the study of anatomy, studiously searching after the properties of the component parts of animals and their difference, and all this he did, as we mentioned above, by the time he was twenty-one years of age. _Hayy examines the Nature of Bodies._