CLEANTHES (c. 301–232 or 252 B.C.), Stoic philosopher, born at Assos in the Troad, was originally a boxer. With but four drachmae in his possession he came to Athens, where he listened first to the lectures of Crates the Cynic, and then to those of Zeno, the Stoic, supporting himself meanwhile by working all night as water-carrier to a gardener (hence his nickname Φρεάντλης). His power of patient endurance, or perhaps his slowness, earned him the title of “the Ass”; but such was the esteem awakened by his high moral qualities that, on the death of Zeno in 263, he became the leader of the school. He continued, however, to support himself by the labour of his own hands. Among his pupils were his successor, Chrysippus, and Antigonus, king of Macedon, from whom he accepted 2000 minae. The manner of his death was characteristic. A dangerous ulcer had compelled him to fast for a time. Subsequently he continued his abstinence, saying that, as he was already half-way on the road to death, he would not trouble to retrace his steps.
Cleanthes produced very little that was original, though he wrote some fifty works, of which fragments have come down to us. The principal is the large portion of the Hymn to Zeus which has been preserved in Stobaeus. He regarded the sun as the abode of God, the intelligent providence, or (in accordance with Stoical materialism) the vivifying fire or aether of the universe. Virtue, he taught, is life according to nature; but pleasure is not according to nature. He originated a new theory as to the individual existence of the human soul; he held that the degree of its vitality after death depends upon the degree of its vitality in this life. The principal fragments of Cleanthes’s works are contained in Diogenes Laertius and Stobaeus; some may be found in Cicero and Seneca.
See G. C. Mohinke, Kleanthes der Stoiker (Greifswald, 1814); C. Wachsmuth, Commentationes de Zenone Citiensi et Cleanthe Assio (Göttingen, 1874–1875); A. C. Pearson, Fragments of Zeno and Cleanthes (Camb., 1891); article by E. Wellmann in Ersch and Gruber’s Allgemeine Encyklopädie; R. Hirzel, Untersuchungen zu Ciceros philosophischen Schriften, ii. (1882), containing a vindication of the originality of Cleanthes; A. B. Krische, Forschungen auf dem Gebiete der alten Philosophie (1840); also works quoted under Stoics.