Titus, Bishop of Bostra, was a redoubtable fourth-century theological polemicist deeply influenced by Greek thought. His chief work, Contra Manicheos, exists in two versions: in Greek, and more completely, in Syriac. This volume contains both, as well as the letters of Pope Julius I and a brief exposition of the faith by Gregory the Thaumaturge. Titus argues against dualism in general, holds that the eternal existence of a devil is contrary to divine providence, justifies the Old Testament, and explains the New Law of Christianity.