(c. 412-323 BC) Ascetic Greek philosopher of the Cynic school. He believed in freedom and self-sufficiency for the individual, and that the virtuous life was the simple life; he did not believe in social mores. His writings do not survive.
He was born in Sinope, Asia Minor, on the Black Sea, captured by pirates, and sold as a slave to a Corinthian named Xeniades, who appointed Diogenes tutor to his two sons. He spent the rest of his life in Corinth. He is said to have carried a lamp during the daytime, looking for one honest man. The story of his having lived in a barrel arose when Seneca said that was where a man so crabbed ought to have lived.