The emperors Constantius (353-361) and Valens (364-378), were advocates of the Arian heresy, which had been condemned at the First Ecumenical Council at Nicea in the year 325. Under their patronage the Arians began a persecution against the Orthodox. Saint Zeno bravely endured all the oppression from the heretics.
In his sermons and letters he firmly asserted the Orthodox teaching about the Lord Jesus Christ as the Only-Begotten Son of God, born of the Father before all ages. Saint Zeno wrote sixteen long and seventy-seven short discourses and directives. He died around the year 360.
Saint Gregory Dialogus (March 12) speaks of a miracle in the year 558 on Saint Zeno’s Feast day. There were spring floods in Italy. The River Tiber overflowed its banks and inundated the surrounding area. The River Atesis flowing past Verona also flooded. The water reached the church built in honor of the hieromartyr Zeno, and came up to the windows of the church. The doors of the temple were open, but the water did not rush inside. It stopped at the wall, and did not harm the church.