He was a man of great genius and extensive learning; it is not known whose pupil he was, nor are any of his disciples mentioned except Gorgias. He was well versed in the tenets of the Eleatic and Pythagorean schools; but he did not adopt the fundamental principles of either; though he agreed with Pythagoras in his belief in the metempsychosis, in the influence of numbers, and in one or two other points; and with the Eleatics in disbelieving that anything could be generated out of nothing. Aristotle speaks of him as very much resembling in his opinions Democritus and Anaxagoras. He was the first who established the number of four elements, which had been previously pointed out one by one, partly as fundamental substances, and partly as transitive changes of things coming into existence. He first suggested the idea of two opposite directions of the moving power, an attractive and a repelling one: and he believed that originally these two coexisted in a state of repose and inactivity. He also assumed a periodical change of the formation of the world; or perhaps, like the philosophers of the pure Ionic school, a perpetual continuance of pure fundamental substances; to which the parts of the world that are tired of change return, and prepare the formation of the sphere for the next period of the world. Like the Eleatics, he strove to purify the notion of the Deity, saying that he, “being a holy infinite spirit, not encumbered with limbs, passes through the world with rapid thoughts.” At the same time he speaks of the eternal power of Necessity as an ancient decree of the Gods, though it is not quite clear what he understood by this term. _Diagoras_ was a native of Melos, and a pupil of Democritus, and flourished about B.C. 435. He is remarkable as having been regarded by all antiquity as an Atheist. In his youth he had some reputation as a lyric poet; so that he is sometimes classed with Pindar, Simonides, and Bacchylides. Aristophanes, in the Clouds, alludes to him where he calls Socrates “the Melian;” not that he was so, but he means to hint that Socrates was an atheist as well as the Melian Diagoras. He lived at Athens for many years till B.C. 411, when he fled from a prosecution instituted against him for impiety, according to Diodorus, but probably for some offence of a political nature; perhaps connected with the mutilation of the Hermæ.