POTAMIO. – First bishop of Lisbon, died in 360. As in the case of Priscillian, a critical disagreement exists regarding P.’s literary personality between the testimonies of his contemporaries and the ideology of his writings.
Those discovered thus far commend him for his unassailable orthodoxy. On the other hand, a group of contemporary writers, including the Luciferians Faustino and Marcellino and St. Hilary of Poitiers, attribute to him the drafting of the second formula of Sirmium (357), together with Osio, bishop of Cordova (PL. 10, 487), and Febadio of Agen (357–58). Perhaps what most clearly condemns P. is a fragment of a letter written to him by St. Athanasius and recently brought to prominence, in which the Saint plainly accuses him of regarding Christ as a creature, thus denying his divinity: «... qua ratione ille ipse quem creaturam putas, caro sit factus ex virgine...» (Epistola ad Potassium episcopum, in Alcuino, Liber adversus haeresim Felicis, 61: PL. 101, 113). Perhaps P., too, an affected and extravagant stylist, orthodox in his first period, later turned to Arianism out of greed for certain possessions, subscribed, without having authored it, to the second formula of Sirmium, and led Osio astray. Ignored by ancient literature and not an insignificant actor during the Arian struggles, P. left, as a brief literary legacy from his early years as a writer, two sermons: De Lazaro or De martyrio Easiae prophetiae, and two dogmatic letters: Epistola ad Athanasium episcopum and De substantia Patris et Filii et Spiritus Sancti.