Gennadius I was Patriarch of Constantinople from 458 to 471, during the reign of the Emperor Leo I (457-474). A presbyter of the church of Constantinople before his elevation, he succeeded Anatolius on the patriarchal throne and was in turn succeeded by Acacius. The sources describe him as distinguished for mildness, tolerance, purity, and abstinence, and he is remembered above all as a reforming pastor concerned with the discipline and formation of the clergy. He is commemorated on August 31.
Gennadius is noted for his strict standards for ordination: according to the synaxarion he refused to ordain any presbyter who had not learned the Psalter and could not interpret the Scriptures. He convened a synod in 459 that condemned simony, and the resulting encyclical against the buying and selling of holy orders was later received with conciliar authority. He also acted against heresy, defending the Orthodox faith against the Eutychian and Monophysite currents of the period.
His life and reputation are preserved in part through The Spiritual Meadow, the collection compiled in the early Byzantine monastic tradition, in which accounts associated with monks who had served under his patriarchate were recorded. After thirteen years as patriarch he is reported to have left Constantinople, by some accounts on account of his health, and to have reposed in 471.
