Saint Cyril was born in Alexandria in the year 376. He was instructed in the faith by his uncle Theophilus, Patriarch of Alexandria. Cyril succeeded to the patriarchal throne himself in 412. When Nestorius began teaching his heresy, Cyril was a leader in the Orthodox opposition. He presided over the Third Ecumenical Council which anathematized Nestorius. He reposed in the year 444. His feast is celebrated on January 18, together with Saint Athanasius of Alexandria.