Roman Catholic Pope Leo’s Letter to Flavian (449)
While emperor Theodosius II initially sup- ported the teaching of Eutyches, Constantinople’s bishop Flavian sought the support of the Roman Catholic Pope Leo (440-461). Leo wrote a letter to Flavian explaining the Roman Catholic’s teaching concerning the person of Jesus Christ. It was meant to be read at the Ecumenical Church Council in Ephesus in 449, but never was. However, in 451, it became a primary document for the Chalcedon Creed.