CLEANTHES klĭ an’ thez (Κλεάνθης), son of Phanius of Assos and head of the Stoic school in Athens from 263-232 b.c.

His Hymn to Zeus, a surviving poem, contains the words quoted by Paul in his address before the Areopagus Court (Acts 17:28). He made Stoicism more religious in its orientation by teaching that the universe was a living being, that God was its soul, and that the sun was its heart. He taught detachment from moral concerns. Doing good for gain was like feeding cattle for meat. He also maintained that evil thoughts were worse than evil deeds, just as a tumor which does not break open is more dangerous than one which does.