Cleanthes
a Greek Stoic philosopher of the 3d century B. C. He was a native of Assus, in Lydia; but, visiting Athens, he became a zealous disciple of Zeno, and to enable him to attend on that master in the day, he was accustomed to labor by night. His mental and bodily strength was immense, and despite all obstacles, he studied so successfully as to become, 263 B. C., Zeno's successor. Of his writings only some fragments remain, among which is his noble "Hymn to Zeus."
CLEARCHUS (klē-ärkus), a Spartan general who commanded about 13,000 Greeks in the army of Cyrus the Younger when he tried to conquer the throne of Persia from his brother, Artaxerxes II. When Cyrus was defeated at Cunaxa (401 в. c.), Clearchus and his chief officers were seized by treachery and put to death.