ARETHAS (c. 86o-94o), Byzantine theological writer and scholar, archbishop of Caesarea in Cappadocia, was born at Patrae. He was a pupil of Photius, and was the author of a Greek commentary on the Apocalypse avowedly based upon that of Andrew, the previous archbishop. He annotated the margins of his classical texts with numerous scholia (many of which are pre served), and had several mss. copied at his own expense, amongst them the Codex Clarkianus of Plato (brought to England from the monastery of St. John in Patmos), and the Dorvillian ms. of Euclid (now at Oxford).
Most divergent opinions have been held as to the time in which Arethas lived; the reasons for the dates given above will be found succinctly stated in the article "Aretas," by A. Jiilicher in Pauly Wissowa's Realencyklopiidie der klassischen Altertumswissenschaft (1896). The text of the commentary is given in Migne, Patrologia Graeca, cvi.