His great pupil never forgot his master during his victorious career, and Alexander is said to have sent Aristoteles the enormous sum of eight hundred talents to prosecute his studies in natural history. He, moreover, ordered several thousands of persons over the whole of Greece and Asia, who lived by hunting, bird-catching, and fishing, or who had the care of parks, herds, hives, stews, and aviaries, to furnish Aristoteles with materials for a work on animals. Two volumes on plants were written by Aristoteles, but they are lost to us; and he influenced the botanists of his day by his great exactitude of description and observation. Aristoteles’ writings and teaching embraced a great variety of subjects, and they were so genuine that he became the leader of one of the principal schools of Greece; and his method of study and many of his facts and ideas have influenced mankind down to the present day. His works were much studied during the Middle Ages, and although his books on botany have been lost, still he influenced the study of botany through his pupil, Theophrastus, who became the great light of after years. There is one point about Aristoteles’ character which everybody must admire, and it was the gratitude he felt for the good friends of his youth and of the days of struggling upwards in his career. It has been noticed that he was brought up by kind people. They were not relations, but probably were appointed his guardians by his father. They were Proxenus and his wife, citizens of Atarneus, who had left that city and had been long resident in Stageira. Not only were they the good friends of the boy, but they evidently brought him in contact with Hermeias, who subsequently became the prince of the place and Aristoteles’ fast friend and brother-in-law. Aristoteles testified his gratitude to his friends by directing in his will that statues of them, as well as of his parents, should be set up at his expense. He likewise educated their son, Nicanor, to whom he gave his daughter in marriage. Whilst growing old he wrote a beautiful poem, which is still to be read, praising the virtues of his friend and patron, Hermeias.