A native of Antioch and pupil of Silvanus of Tarsus and Eusebius of Emesa, Diodore completed his studies at Athens. A monk and then priest in his city, he had occasion to dispute with the emperor Julian 362– 363. In the Antiochene schism he sided with Meletius, and with Flavian he headed the Meletian community after Meletius was exiled first by Constantius II and then by Valens until he too was exiled to Armenia 372. After Valens’s death he was ordained bishop of Tarsus 378 and played a prominent part in the Council of Constantinople of 381. He died before 394, when his fame as an exegete and theologian was great. At the time of the Nestorian controversy, however, he was considered among Nestorius’s precursors and was subjected to violent attacks, including some by Cyril, until he too became involved, though only indirectly, in the condemnation of the Three Chapters 553. The condemnation led to the disappearance of all of his writings, which from various sources Jerome, Ebedjesu, Suidas we know to have been very numerous, and of which only fragments remain, with perhaps one exception see below. Astronomy was the subject of Against the Astronomers, the Astrologers and Fate and other works among them one against Aristotle’s “fifth substance” against determinism and astral fatalism in defense of divine providence. A great many doctrinal works were directed against pagan philosophical doctrines on God, nature, matter Against Plato on God and the Gods; On Nature and Matter; On God and the False Matter of the Greeks; against Arians and Macedonians On the Unity of God; On the Holy Spirit; some addressed other theological problems On the Resurrection of the Dead; On the Soul. Very important was his Against the Synousiasts, i.e., the Apollinarists, since it was in polemic with them that the Antiochenes most stressed the distinction between divinity and humanity in Christ, thus incurring the charge of Nestorianism ante litteram.