St Leo I

St Leo I, called The Great (c. 400-461), pope (440-461), the greatest administrator of the ancient Church, who established the primacy of the bishop of Rome over other bishops.

Leo was probably born in Tuscany, and he was active as a cleric in Rome long before his election to the papacy. He was consecrated bishop of Rome on September 29, 440, at a time of political disintegration in the West, succeeding Sixtus III. He concentrated on creating a strong central government in the Church and suppressing heresy. His influence was shown by his ability to convoke (451) a synod of bishops in Milan, the strongest see in northern Italy outside his own metropolitan jurisdiction. When Bishop Hilary of Arles challenged Leo in a synod in Rome, Leo had him confined to his diocese by imperial decree. Leo persuaded Attila the Hun not to invade Rome in 452 and Gaiseric the Vandal not to sack the city in 455.

Leo was equally assertive in the East, although he did not always receive the same imperial, or even episcopal, support. His greatest triumph there was the Council of Chalcedon (451), over which his own legates presided. The council was summoned to condemn the heresy Eutychianism, a form of Monophysitism, the doctrine that Christ has only one (divine) nature, advocated by the Byzantine monk Eutyches. Leo's definition of the “two natures” (divine and human) of Christ in his Tome (449), his doctrinal letter to the patriarch of Constantinople, was endorsed by the council with the famous words “Peter has spoken through Leo”.

Leo's surviving sermons and letters convey clear formulations of belief and discipline without being otherwise exceptional. His great administrative accomplishment was to conjoin ecclesiastical procedures and papal primacy with Roman law. He died in Rome on November 10, 461; his feast day is November 10. Leo was proclaimed a Doctor of the Church in 1574.