Author of an Apology for Christianity originally written in Greek and addressed to an unnamed emperor ( CPG 1062). The complete text is preserved only in Syriac translation, ed. with ET, J. R. Harris (1891), since the original Greek is lost apart from two 4th-cent. papyrus fragments and a much later adaptation, when the work was incorporated into the Life of Barlaam and Josaphat (a tale of Buddhist origin), ascribed to John of Damascus (ed. R. Volk, PTS 60; 2006). The unique ms. containing the Syriac text, ms. Sinai Syr. 16, should probably be dated to the 7th cent.