ARETHAS (c.860-940), Byzantine theological writer and scholar, archbishop of Caesarea in Cappadocia, was born at Patrae. He was the author of a Greek commentary on the Apocalypse, avowedly based upon that of Andrew, his predecessor in the archbishopric. In spite of its author's modest estimate, Arethas's work is by no means a slavish compilation; it contains additions from other sources, and especial care has been taken in verifying the references. His interest was not, however, confined to theological literature; he annotated the margins of his classical texts with numerous scholia (many of which are preserved), 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. Jülicher in Pauly-Wissowa's Realencyclopadie der klassischen Altertumswissenschaft (1896). The text of the commentary is given in Migne, Patrologia Graeca, cvi.; see also O. Gebhardt and A. Harnack, Texte und Untersuchungen zur Geschichte der altchristlichen Litt. i. pp. 36-46 (1882), and Vita Euthymii (patriarch of Constantinople, d. 917), ed. C. de Boor (1888); H. Wace, Dictionary of Christian Biography, i.; C. Krumbacher, Geschichte der byzantinischen Litteratur (1897); G. Heinrici in Herzog-Hauck, Realencyklopadie (1897).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)