Gennadius I, Saint, Patriarch of Constantinople (458-471), has left scarcely any writings. Facundus (Defensio, II, iv) states that he wrote against St. Cyril of Alexandria, probably in 431-2, and quotes a passage to show that his work was more violent even than the letter of Ibas. If St. Cyril’s letter of 434 (Ep. lvi) is to the same Gennadius, they were friends in that year. Gennadius succeeded Anatolius as Bishop of Constantinople in 458. On June 17, 460, St. Leo wrote to him (Ep. clxx) warning him against Timothy Aelurus, the Monophysite who had made himself Patriarch of Alexandria. Not later, it seems, than 459 St. Gennadius celebrated a great council of eighty-one bishops, many of whom were from the East and even from Egypt, including those who had been dispossessed of their sees by Aelurus. The letter of this council against simony is still preserved (Mansi, VII, 912). About the same time St. Daniel the Stylite began to live on a column near Constantinople, apparently without the patriarch’s leave, and certainly without the permission of Gelasius, the owner of the property where the pillar stood, who strongly objected to this strange invasion of his land. The Emperor Leo protected the ascetic, and some time later sent St. Gennadius to ordain him priest, which he is said to have done standing at the foot of the column, since St. Daniel objected to being ordained, and refused to let the bishop mount the ladder. At the end of the rite, however, the patriarch ascended to give Holy Communion to the stylite and to receive it from him. Whether he then imposed his hands on him is not said. Possibly he considered it sufficient to extend them from below towards the saint. According to Theodorus Lector, Gennadius would allow no one to become a cleric unless he had learned the Psalter by heart. He made St. Martian aeconomus of the Church of Constantinople.
St. Gennadius is said by Joannes Moschus to have been very mild and of great purity. We are told by Gennadius of Marseilles that he was lingua nitidus et ingenio acer, and so rich in knowledge of the ancients that he composed a commentary on the whole Book of Daniel. The continuation of St. Jerome’s Chronicle by Marcellinus Comes tells us (according to some manuscripts) that Gennadius commented on all St. Paul’s Epistles. Some fragments are collected in Migne, P.G., LXXXV, chiefly from the two catenae of Cramer on Romans; a few passages are found in the catena of Oecumenius, and a few in the Vienna MS. gr. 166 (46). Some fragments in the catenae of Nicephorus show that Gennadius also commented on Genesis. He is seen to have been a learned writer, who followed the Antiochene school of literal exegesis. He is celebrated in the Greek Menaea on August 25 and November 17; and on the former day in the Roman Martyrology.