Photios I c. 810 – 893

Photios I, called the Great, was a Byzantine philosopher, theologian, and twice Patriarch of Constantinople, the most learned man of ninth-century Byzantium and one of the principal figures in the long Eastern Christian effort to harmonize the inheritance of classical philosophy with Christian theology. His Bibliotheca, an encyclopedia of summaries and excerpts from some 280 ancient works, has preserved much of what we know of late antique literature, while his Mystagogy of the Holy Spirit gave the classical Eastern Christian rebuttal of the Latin Filioque doctrine. His ecclesiastical and intellectual leadership shaped the Byzantine philosophical and theological tradition for centuries.

Photios was born around 810 at Constantinople into one of the most distinguished families of the empire, closely connected to the iconophile party and to the imperial house of Theophilos. He held high office in the imperial chancery — first secretary, then protospatharios and ambassador to the Abbasid court — and was already renowned as the most learned man of his generation when in December 858 he was consecrated patriarch of Constantinople in succession to Ignatios. He was deposed in 867 in the reaction that followed the murder of Michael III, recalled and reinstated by Basil I in 877, and finally deposed again by the new emperor Leo VI in 886; he died in exile at the monastery of Bordi in Armenia around 893.

His writings include the Bibliotheca, two hundred and eighty critical reviews of pagan and Christian works, many of them now lost; the Mystagogia of the Holy Spirit, the central Greek refutation of the Latin Filioque; the Amphilochia, a collection of doctrinal answers; the Lexicon; and a corpus of homilies and letters.

Photios was the leading figure of the ninth-century Byzantine intellectual revival, the principal opponent of the papal claim to universal jurisdiction in the Photian schism that anticipated the later break of 1054, and the patron of the Slavic mission of his former pupils Cyril and Methodius. The Eastern Orthodox churches commemorate him as Saint Photios the Great.