a Greek philosopher, was the son of Cleisthenes, a man of poor means, but of noble birth, and was born about 300 B.C. at Eretria, the capital of Euboea. According to his biographer Diogenes Laertius, he was trained by his father to the trade of building and tent-making. But Athenaeus represents him in his younger years as a miller, grinding in the mill all night, and studying philosophy during the day. A military appointment which he received at Megara gave him an opportunity of prosecuting his favourite study under Stilpo. He then repaired to Elis, and became a disciple of the Elean school of philosophy, which had recently been founded by Phaedo. On his return to Eretria, Menedemus became a teacher of the doctrines he had learned at Elis. His character probably prevented an immediate rise in his new vocation, but was no doubt the means of his ultimate success. He was grave and taciturn, satirical, and disposed to rebuke every misdemeanour by a stinging sarcasm; fiery in temper, and declaiming frequently till he became black in the face. As he was indistinct in his elocution, we may infer that he was not very fascinating in his prelections. Yet his open and sterling disposition, and the satisfactory nature of his instructions, raised him to so great an eminence that the doctrines which he taught became identified with his school, and the Elean philosophy came to be called the Eretrian. In the same slow and sure manner did he rise to the highest civil offices. While Menedemus was thus acquiring fame and riches he was living in the same house with Asclepiades, the long-tried friend who had been his companion in his early hardships, and who was now admitted to be his companion in his good fortune. The avowed favour of Menedemus for Antigonus Gonatas led him to be suspected of a design to betray Eretria into that monarch's power. With the intention of vindicating his patriotism, he repaired to Antigonus, and besought him to Menehould restore his country to freedom; but meeting with a refusal, he starved himself to death, at the age of seventy-four.

As Menedemus did not commit his opinions to writing, the distinctive principles of the Eretrian school have been very partially and very vaguely ascertained. From Diogenes Laertius, however, we know that they resembled the school of Megara in the extreme and frivolous subtlety of their dialectics. Adopting also the Megarian doctrine, that existence was of necessity simple, and was therefore knowable only by direct cognition, they rejected all negative and hypothetical propositions. The same extreme generalization they employed in evolving a system of ethics. After taking an articulate distinction between the good and the useful, they proceeded to prove that all the virtues, though considered by ordinary thinking to be distinct from each other, are merely different forms of one idea, and are therefore essentially identical. They concluded their ethical system with asserting the complete identity of the good and the true.