Reading from the Synaxarion:

Photius the Great, Patriarch of Constantinople

As for the thrice-blessed Photius, the great and most resplendent Father and teacher of the Church, the Confessor of the Faith and Equal to the Apostles, he lived during the years of the emperors Michael (the son of Theophilus), Basil the Macedonian, and Leo his son. He was the son of pious parents, Sergius and Irene, who suffered for the Faith under the Iconoclast Emperor Theophilus; he was also a nephew of Saint Tarasius, Patriarch of Constantinople (see Feb. 25). He was born in Constantinople, where he excelled in the foremost imperial ministries, while ever practicing a virtuous and godly life. An upright and honorable man of singular learning and erudition, he was raised to the apostolic, ecumenical, and patriarchal throne of Constantinople in the year 857.

The many struggles that this thrice-blessed one undertook for the Orthodox Faith against the Manichaeans, the Iconoclasts, and other heretics, and the attacks and assaults that he endured from Nicholas I, the haughty and ambitious Pope of Rome, and the great persecutions and distresses he suffered, are beyond number. Contending against the Latin error of the filioque, that is, the doctrine that the Holy Spirit proceeds from both the Father and the Son, he demonstrated clearly with his Mystagogy on the Holy Spirit how the filioque destroys the unity and equality of the Trinity. He has left us many theological writings, panegyric homilies, and epistles, including one to Boris, the Sovereign of Bulgaria, in which he set forth for him the history and teachings of the Seven Ecumenical Councils. Having tended the Church of Christ in holiness and in an evangelical manner, and with fervent zeal having rooted out all the tares of every alien teaching, he departed to the Lord in the Monastery of the Armenians on February 6, 891.