PAPÀ BAR 'AGGAJ. — Bishop of Seleucia-Ctesiphon, he occupied the see of the capital of Sassanian Persia at the time of Constantine.
The sources attribute to him hegemonic tendencies over all the dioceses of Persia; thus the Synodicon orientale, the Chronicle of Seert, and that of Mârî b. Sulaimân. Although the sources are very discrepant in detail and full of anachronisms, the fact that P. obtained, with the help of the Western Fathers, i.e., the bishops of the province of Antioch, a certain primacy over all the bishoprics of Persia, is beyond doubt.
BIBL.: H. Gismondi, Maris Amri et Slibae de patriarchis nestorianorum commentaria, I, Rome 1899, p. 7; J.-B. Chabot, Synodicon orientale, Paris 1902, pp. 289-91; T. Sachau, Die Chronik von Arbela, Berlin 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