Christian Heresies of the
Ninth Century:

Greek Schism:  
    Its origin dates from the time of Photius, 858. The Greek Orthodox Church or, more correctly, the Orthodox Eastern Church, Greek-Russian, denies the supremacy of the Pope, holds that the Catholic Church erred in prescribing celibacy for the clergy, and teaches that the Holy Ghost proceeds from the Father alone.. A council at Rome deposed and excommunicated Photius.
    This independent church is the result of what is known in history as the "Greek Schism". Its origin dates from the time of Photius, a high official in the civil service of the Byzantine government, distinguished for his learning and literary taste. In 858, on the deposition of Ignatius, he was hurried through all the ecclesiastical degrees and installed by the Emperor Michael III as Patriarch of Constantinople. Pope Nicholas I objected to the irregularities of Photius’ elevation, and convoked a council at Rome which deposed and excommunicated him. Photius then gave the conflict a doctrinal turn and brought about conditions that paved the way for the Great Schism between the Eastern and Western Churches in the 11th century.
    Photius was deposed and sent into exile several times, the last being in 886, and a few years later died in an Armenian monastery.
    The schism commenced by him, although suppressed several times, continues to the present day.
    Orthodox