At Edessa the result of the conflict between the Nestorians and their opponents was long doubtful. When Rabbala, the fierce anti-Nestorian and friend of Cyril, died in 435, he was succeeded in the bishopric by Ibas, who as head of the famous "Persian school" in the city had done much to inculcate on his pupils the doctrines of Theodore of Mopsuestia. But the feeling against the Nestorian party grew in strength, till on the death of Ibas in 457 the leading Nestorian teachers were driven out of Edessa. The Persian school continued to exist for another 3 2 years, but was finally closed and destroyed by order of the emperor Zeno in 489. The Nestorian teachers then started a great school at Nisibis (which had been under Persian rule since Jovian's humiliating treaty of 363). By the energetic efforts of Barsauma, bishop of that city, practically the whole church of Persia was won over to the Nestorian creed.
The next bishop of Edessa, Ibas, who succeeded in 435 at the death of Rabbala, proved himself a follower of the Nestorian doctrine. (See above.) As a teacher in the Persian school of Edessa he had translated, probably with the help of his pupils, certain works of "the Interpreter," i.e., Theodore of Mopsuestia. Among these may have been the commentary on St. John of which the complete Syriac version was published by Chabot in 1897. He may possibly have translated a work of Aristotle. To the Nes torian movement in Persia he rendered useful service by his letter to Mari of Beth Hardasher, in which he maintained the tenets of Diodore and Theodore, while allowing that Nestorius had erred. On the ground of his writings he was condemned and deposed by the "robber synod" of Ephesus (449), but was restored by the Council of Chalcedon (451), after he had anathe matized Nestorius. His death in 457 was followed by a strong anti-Nestorian reaction at Edessa, which led to the expulsion of many of the leading teachers.
On Isaac of Antioch, "one of the stars of Syriac literature," see the special article. In spite of his over-diffuseness, he is one of
the most readable of Syriac authors.
A Nestorian contemporary of Isaac, Dadhishoc, who was ca tholicus of Seleucia from 421 to 456, composed commentaries on Daniel, Kings and Ecclesiasticus. His chief importance in the history of the Persian Church lies in his having induced a synod of bishops to declare that church independent of the see of Anti och and of the "Western Fathers." (See J. Labourt, Le Christian isme dans l'empire perse, 1904, p. 122 seq.) The most powerful missionary of Nestorianism during the 2nd half of the 5th century was Barsauma of Nisibis, whom his opponents called "the swimmer among the reeds," i.e., the wild boar. Born probably between 415 and 420 he imbibed Nestorian doctrine from Ibas at the Persian school of Edessa, but was driven out in 457 on the death of his master, and went to be bishop of Nisibis. In a succession of missionary journeys he succeeded, partly by persuasion and partly (if his enemies are to be believed) by violence, in attaching to Nestorianism nearly all the Christian communities of Persia, with the exception of Taghrith, which was always strongly Monophysite. He had many quarrels with his ecclesiastical superior the catholicus of Seleucia, but finally made peace with Acacius soon after the accession of the latter in 484. Among other severities towards the Monophysites, he persuaded the Persian king PerOz to banish many of them into the Roman dominions. One of his great aims was to secure for the Nestorian clergy freedom to marry, and this was finally sanctioned by a council at Seleucia in 486 (Labourt, op. cit., chap. vi.). Barsiuma, must have been bishop of Nisibis for nearly 40 years, but was dead by 496. His writings seem to have been chiefly liturgical; he gave the first set of statutes to the school of Nisibis, which was founded during his bishopric.
His fellow-worker Narsai, whom the Jacobites called "the leper," but the Nestorians "the harp of the Holy Spirit," appar ently accompanied Barsauma, from Edessa to Nisibis, where according to Barhebraeus he lived for so years. Barsauma ap pointed him head of the new school, where he taught rigidly Nestorian doctrine. He was a copious writer, especially in verse. Many of his poems have now been published. (See Mingana, Narsai, homiliae et carmina, 2 vols. Mosul, 1905.) His theo logical position is clearly defined in a homily on the three doctors —Diodore, Theodore and Nestorius—published by the Abbe Martin in the Journal asiatique for July 190o.
To about the same period belongs The book of Hierotheus by the "pantheist" Stephen bar Sildh-aite, which has recently been edited and translated by F. C. Marsh (1927).