Priest and writer. According to a letter from Yaʿqub of Edessa to Yuḥanon of Litarba (Letter 14; ms. Brit. Libr. Add. 12,172, f. 123r–v), Isḥaq was a well-known priest in Edessa who flourished during the time of the emperor Zeno (ca. 474–91). During the time of Peter the Fuller (ca. 471–88), Isḥaq went to Antioch where he became involved in the controversy then raging over the Trisagion. According to Yaʿqub (cf. also, Chronica Minora, vol. 2, 217), Isḥaq saw a man who was carrying around a parrot that had been trained to recite the Trisagion against those who opposed its addition to the liturgy. Isḥaq was so impressed by this sight that he wrote a long memrā on this event. It is the longest memrā in the collection of his works and is perhaps his best known title, though its contents are far less known. It is likely that this is the same Isḥaq whom the Chronicle of Edessa and other sources claim flourished in the 450s. The Chronicle of Michael Rabo (II.viii.9) and the dependent Ecclesiastical Chronicle of Bar ʿEbroyo (I.165) both seem to have conflated this Isḥaq with Isḥaq of Edessa .
To this Isḥaq is attributed a very large corpus of works which remains only partially and incompletely edited. Approximately two hundred works have been identified, nearly all of which are memre written in the seven syllable meter. Many are on ascetic subjects, although there are many on biblical and theological themes. Some of these works have also been combed for the data they reveal on contemporary practices of local pagan worship. All the works in this corpus cannot have come from the same hand. Although their early transmission is almost entirely in mss. of W.-Syr. provenance, the later ms. tradition occasionally attributes some of them to the great E.-Syr. mystic Isḥaq of Nineveh .