New Catholic Dictionary – Pope Saint Leo I

detail of a painting of Saint Leo Magnus; by Francisco de Herrera el Mozo, 17th century; Prado Museum, Madrid, Spain; swiped from Wikimedia CommonsArticle

(Latin: leo, lion) Pope Saint Leo the Great Doctor of the Church. Reigned from 440 to 461; died in Rome. A deacon, he was sent to Gaul as mediator by Emperor Valentinian III. Elected when the Western Empire was disintegrating and heresy rife, his chief aim was to sustain church unity. To gain this end he established the vicariates of Arles, as the center of the Gallican episcopacy; and Thessalonica, as the center of Eastern Illyria. He established closer relationships between distant episcopates and Rome, and had the primacy of the Bishop of Rome over the whole Church recognized in an edict of Emperor Valentinian, 445. He combated Pelagianism, Manichaeanism and Priscillianism; upheld the decision of the Patriarch of Constantinople against Eutyches by a dogmatic letter confirming the doctrine of the Incarnation. Later in the general council held at Chalcedon this epistle was accepted as an expression of Catholic Faith concerning the Person of Christ. He reformed Church discipline; built and restored churches; protected Rome from the Huns under Attila and the Vandals under Genseric. He left many sermons and epistles of great historical value. Feast, Roman Calendar, 11 April.

MLA Citation

  • “Pope Saint Leo I”. New Catholic Dictionary. CatholicSaints.Info. 7 October 2012. Web. 23 January 2022. <>