St. Vincent of Lérins and St. Optatus of Milevis

Milevis

May 24 was the feast day of St. Vincent of Lérins, a soldier who became a monk at the monastery in Lérins, and wrote his famous Commonitory in AD 434, three years after the third Ecumenical Council at Ephesus, and seventeen years before the Ecumenical Council of Chalcedon. He wrote to explain the rule he had received, by which the truth of the Catholic faith can be distinguished from the falsehood of heresy. June 4 is the feast of St. Optatus, a fourth-century bishop of Milevis, about ten miles from the Mediterranean Sea on the coast of northern Africa in what is now Algeria. He was a convert to the Catholic faith, and an African by birth. His major work is titled Against the Donatists, written between AD 372 and 375. How are the writings of these two saints related to the ecumenical effort to bring all Christ's followers into full and visible unity? See "The Commonitory of St. Vincent of Lérins" and "St. Optatus on Schism and the Bishop of Rome."