Nicholas I

Nicholas I., surnamed The Great, a Roman by birth, was pontiff from 858 to 867. He was very energetic and ambitious; in 863 he excommunicated Photius of Constantinople, and thus caused the separation between the Eastern and Western Churches. He first founded the claims of the Papacy to universal temporal power on the spurious decretals of Isidore, subjected Lotharius I. to penance, and converted Bogoris of Bulgaria, with his people. In the Roman Church he ranks as a saint.