Leo the Great

Leo was probably born in Tuscany near the end of the fourth century. Before he was bishop he was already one of the most trusted men in the Roman church, a deacon under two popes, entrusted with correspondence that reached as far as Cyril of Alexandria and Augustine's North Africa.

In 440 he was in Gaul on an imperial mission, sent to reconcile two quarreling Roman generals, when word came that Pope Sixtus III had died and he had been elected in his absence. He came back and was consecrated on 29 September 440. He held the office twenty-one years.

His great doctrinal act was a letter. In 449 he wrote to Flavian, bishop of Constantinople, about the teaching of the monk Eutyches, who held that after the incarnation there was only one nature in Christ, the human absorbed into the divine, like a drop in the sea. Leo's letter, always called the Tome, says the opposite in short Latin sentences: one person, two natures, each keeping what properly belongs to it, the divine not diminished and the human not swallowed. 'Each nature performs what is proper to it in communion with the other.'

The council that met at Ephesus later that year refused to read it and reinstated Eutyches by force; Leo called that meeting a den of robbers, and the name stuck. Two years later, at the Council of Chalcedon in 451, the Tome was read aloud to about five hundred bishops, and the record says they answered, 'Peter has spoken through Leo.' The council's definition of Christ as one person in two natures rests on it. Not everyone accepted the result: the churches of Egypt, Syria, Armenia, and Ethiopia rejected Chalcedon and remain separate to this day.

He also faced the collapse of the West. In 452 Attila and the Huns came down through northern Italy, sacking Aquileia. Leo went north with two imperial officials and met Attila near Mantua, on the river Mincio. Attila turned back. Plague, supply failure, and troops on his flank all played a part, but it was the bishop who went out and the army that did not come on. Three years later Genseric and the Vandals reached the gates of Rome itself. Leo could not stop them, but he met Genseric outside the walls and secured a promise: the city would be plundered, not burned, and the people not massacred. For fourteen days Rome was stripped, and Rome survived.

About a hundred and forty-three letters and ninety-six sermons of his are preserved, the earliest large body of papal preaching that survives. He died on 10 November 461 and was buried at St Peter's. He is one of only a handful of popes called 'the Great.'

Sources: Leo the Great, Letters and Sermons (Nicene and Post-Nicene Fathers, second series volume 12); the Acts of the Council of Chalcedon; Prosper of Aquitaine, Chronicle; Philip Schaff, History of the Christian Church.