Diodorus of Tarsus

Diodorus was born at Antioch to a good family, studied at Athens, and came home to run a school — an asketerion, a house of monastic training and biblical study on the edge of the city. Two of his students changed the church: John Chrysostom and Theodore of Mopsuestia. Under the emperor Valens, who backed the Arian party, the orthodox congregation at Antioch lost its churches. Diodorus, still a priest, held them together. They met outside the city walls, at the martyrs' graves and along the riverbank, and he kept preaching. Basil of Caesarea wrote to him with respect during those years. When Valens died and Theodosius came to power, Diodorus was made bishop of Tarsus in 378, and at the Council of Constantinople in 381 the emperor's edict named him as one of the bishops communion with whom defined orthodoxy. His mark on the church is a method of reading the Bible. Alexandria read Scripture allegorically, looking through the literal sense to a hidden spiritual one. Diodorus set the Antiochene school on a different footing: begin with what the text actually says, in its own historical situation, and let any further meaning grow out of that soil rather than replace it. He distinguished theoria, a genuine contemplative sense grounded in the history, from allegoria, which he thought floated free of it. He wrote a treatise titled, in effect, on the difference between the two. That instinct — that a passage means first what it plainly says — passed through his students into the whole later tradition of grammatical and historical exegesis, and it is the working assumption of most serious Bible study to this day. His reputation did not survive him. Theodore of Mopsuestia, his pupil, was later blamed as the father of Nestorianism, and the blame ran backward. Cyril of Alexandria wrote against Diodorus by name. In 499 a synod condemned him, and after Constantinople II in 553 his books were no longer copied. Almost his entire output — commentaries on the whole Old Testament and much of the New, works against fate and astrology, against the Manichaeans, and a defense of the faith against the emperor Julian — is lost. Fragments survive in catenae, and a commentary on the Psalms has been recovered. The Church of the East, which never accepted his condemnation, has honored him without a break. Sources: Socrates Scholasticus, Ecclesiastical History, VI.3; Theodoret of Cyrus, Ecclesiastical History, IV.24–25; Jerome, On Illustrious Men, 119; The Catholic Encyclopedia (1913), s.v. "Diodorus of Tarsus".