Leo I, Saint


Also found in: Dictionary, Thesaurus.

Leo I, Saint

(Saint Leo the Great), c.400–461, pope (440–61), an Italian; successor of St. Sixtus III. A Doctor of the Church, he was one of the greatest pontiffs of the early years of the church. He waged a firm campaign against schism and heresy. With the aid of Valentinian IIIValentinian III,
419–55, Roman emperor of the West (425–55). Two years after the death of his uncle, Honorius, he was placed on the throne by his cousin Theodosius II, who deposed the usurper John.
..... Click the link for more information.
, the Roman emperor of the West, he campaigned to eliminate Manichaeism from Italy. Later, asserting his authority over St. Hilary of ArlesHilary of Arles, Saint
, d. 449, Gallo-Roman churchman. Forsaking riches, he entered the monastery at Lérins. He was made archbishop of Arles (c.429) against his wishes. As head of the church in Gaul, Hilary hastily deposed two bishops.
..... Click the link for more information.
, he obtained an imperial rescript that effectively confirmed the authority of the pope over all his bishops. In the Nestorian-Monophysite controversy Leo was the leader in defending Catholic teaching. He wrote the celebrated Tome of Leo, a doctrinal letter defining the two natures and one person of Christ that was later adopted as ecumenical at Chalcedon (see Chalcedon, Council ofChalcedon, Council of,
fourth ecumenical council, convened in 451 by Pulcheria and Marcian, empress and emperor of the East, to settle the scandal of the Robber Synod and to discuss Eutychianism (see Eutyches).
..... Click the link for more information.
), when the heresiarch Eutyches was condemned. He was also effective as a statesman and met (452) AttilaAttila
, d. 453, king of the Huns (445–53). After 434 he was coruler with his brother, whom he murdered in 445. In 434, Attila obtained tribute and great concessions for the Huns in a treaty with the Eastern Roman emperor Theodosius II, but, taking advantage of Roman wars
..... Click the link for more information.
 the Hun to persuade him not to invade Rome. In 455 he similarly urged Gaiseric the Vandal to spare the lives of the Romans. St. Leo's letters and sermons reflect the many aspects of his career and personality, including his great personal influence for good, and are invaluable historical sources. His rhythmic prose style, called cursus leonicus, influenced ecclesiastical language for centuries. The celebrated Leonian Sacramentary, the oldest form of the Roman Missal, is probably not his work. He was succeeded by St. Hilary. Feast: Apr. 11.