(Εὐκλείδης), a native of MEGARA, or, according to some less probable accounts, of Gela. He was one of the chief of the disciples of Socrates, but before becoming such, he had studied the doctrines, and especially the dialectics, of the Eleatics. Socrates on one occasion reproved him for his fondness for subtle and captious disputes. (D. L. 2.30.) On the death of Socrates (B. C. 399), Eucleides, with most of the other pupils of that philosopher, took refuge in Megara, and there established a school which distinguished itself chiefly by the cultivation of dialectics. The doctrines of the Eleatics formed the basis of his philosophical system. With these he blended the ethical and dialectical principles of Socrates. The Eleatic dogma, that there is one universal, unchangeable existence, he viewed in a moral aspect, calling this one existence the Good, but giving it also other names (as Reason, Intelligence, &c.), perhaps for the purpose of explaining how the real. though one, appeared to be many. He rejected demonstration, attacking not so much the premises assumed as the conclusions drawn, and also reasoning from analogy. He is said to have been a main of a somewhat indolent and procrastinating disposition. He was the author of six dialogues, none of which, however, have come down to us. He has frequently been erroneously confounded with the mathematician of the same name. The school which lie founded was called sometimes the Megaric, sometimes the Dialectic or Eristic. (D. L. 2.106_108; Cic. Aead. 2.42; Plut. de Fratr. Am. 18.)