DEMOCEDES was a celebrated physician of Crotona, in Magna Grecia, who lived in the sixth century B.C. He went to practise at Ægina, where he received from the public treasury a sum equal to about £344 a year for his services. The next year he went to Athens at a salary equal to £406, and the following year he went to the island of Samos. The tyrant Polycrates gave him the salary of two talents. He was carried prisoner to Susa to the court of Darius, where he acquired a great reputation and much wealth by curing the king’s foot and the breast of the queen. It is recorded that Darius ordered the surgeons who had failed to cure him to be put to death, but Democedes interceded for and saved them. He ultimately escaped to Crotona, where he settled, the Persians having in vain demanded his return.[367] He wrote a work on medicine. DEMOCRITUS, of Abdera, was a contemporary of Socrates; he was born between 494 and 460 B.C., and was one of the founders of the Atomic philosophy. He was profoundly versed in all the knowledge of his time. So ardent a student was he, that he once said that he preferred the discovery of a true cause to the possession of the kingdom of Persia. The highest object of scientific investigation he held to be the _discovery of causes_. He wrote on medicine, and devoted himself zealously to the study of anatomy and physiology. Pliny says that he composed a special treatise on the structure of the chameleon.[368] He wrote on canine rabies, and on the influence of music in the treatment of disease. He is, however, best known to science on account of his cosmical theory. All that exists is vacuum and atoms. The atoms are the ultimate material of all things, even of spirit. They are uncaused and eternal, invisible, yet extended, heavy and impenetrable. They are in constant motion, and have been so from all eternity. By their motion the world and all it contains was produced. Soul and fire are of the same nature, of small, smooth, round atoms, and it is by inhaling and exhaling these that life is maintained. The soul perishes with the body. He rejected all theology and popular mythology. Reason had nothing to do with the creation of the world, and he said, “There is nothing true; and if there is, we do not know it.” “We know nothing, not even if there is anything to know.” He died in great honour, yet in poverty, at an advanced age (some writers say at 109 years). His knowledge of nature, and especially of medicine, caused him to be considered a sorcerer and a magician. There was a tradition that he deprived himself of his sight in order to be undisturbed in his intellectual speculations. He probably became blind by too close attention to study. Another story was that he was considered to be insane, and Hippocrates was sent for to cure him.