The pope whose Tome shaped the definition of Christ at Chalcedon and who, by tradition, turned Attila the Hun away from Rome — a founder of the medieval papacy.
Life
Leo I (pope 440–461) asserted the authority of the Roman see and articulated, in his Tome, the doctrine of Christ's two natures in one person that the Council of Chalcedon (451) adopted as orthodoxy. By tradition he confronted Attila the Hun in 452 and persuaded him to spare Rome, and later interceded during the Vandal sack. A Doctor of the Church and one of only a few popes called "the Great," he did much to define the papacy's spiritual and temporal role.