Cath. (1318–53?) and author. His baptismal name was Yawsep. Previously metropolitan of Erbil ( Arbela ), he was elected cath. at the Synod of 1318, and was the last cath. to be enthroned in the Church of Mar Mari in Kokhe (on the opposite bank of the Tigris to Ctesiphon). His treatise ‘On the Ecclesiastical Mysteries’, in 7 Books, remains an authoritative source up to the present day in the Ch. of E. The 7 Books cover: the Priesthood, the Consecration of the Church, Baptism, Eucharist, ‘the mystery of the perfecting of ministers’ (ordination), funeral rites, and betrothal-marriage (a detailed list of contents is given in Assemani, BibOr, III.1, 572–9).