PAPÀ BAR 'AGGAJ. - Bishop of Seleucia-Ctesiphon, he occupied the see of the capital of Sassanid Persia in the time of Constantine.
The sources attribute hegemonic tendencies over all the dioceses of Persia to him; thus the Synodicon orientale, the Chronicle of Seert, and that of Mâri b. Sulajmân. Although the sources differ greatly in their particulars and are full of anachronisms, there is no doubt that P., with the help of the « Western Fathers », that is, the bishops of the province of Antioch, obtained a certain primacy over all the bishoprics of Persia.
BIBL.: H. Gismondi, Maris Amri et Slibae de patriarchis nestorianorum commentaria, I, Roma 1899, p. 7; J.-B. Chabot, Synodicon orientale, Parigi 1902, pp. 289-91; T. Sachau, Die Chronik von Arbela, Berlino 1915, pp. 71-72; A. Scher, Histoire nestorienne: PO 4, 296; I. Ortiz de Urbina, Storia e cause dello scisma della Chiesa di Persia, in Or. chr. per., 3 (1937), pp. 613-67. Guglielmo de Vries