Leo the Great

Leo the Great was the Bishop of Rome whose Tome to Flavian provided the Christological formula adopted by the Council of Chalcedon in 451 — that Christ is one person in two natures, divine and human, 'without confusion, without change, without division, without separation.' He is also the pope who confronted Attila the Hun outside Rome in 452 and persuaded him to withdraw, and who negotiated with Genseric the Vandal in 455 to limit the sacking of Rome. Leo combined theological precision, pastoral authority, and political courage in a way that defined the papacy for centuries.

Traditionally, when Leo confronted Attila, the Hun king saw a vision of Saints Peter and Paul standing behind the pope with drawn swords, threatening divine vengeance if Rome were attacked. The story first appears in the Liber Pontificalis and was later depicted by Raphael in the Vatican Stanze. Whether the tradition reflects a genuine visionary experience or is legendary embellishment, it captures the conviction that Leo's authority transcended the merely political.

Leo was born around 400, probably in Tuscany, and rose through the Roman clergy to become an influential deacon. He was elected pope in 440 while on a diplomatic mission to Gaul, and served for twenty-one years — one of the longest and most consequential pontificates in history.

His theological achievement centers on the Tome — a letter sent to Flavian, Patriarch of Constantinople, in 449 in response to the heresy of Eutyches, who had so emphasized Christ's unified person that he effectively absorbed Christ's human nature into his divine nature. Leo's response was a masterpiece of theological clarity: 'Each nature performs its proper functions in communion with the other: the Word does what pertains to the Word, the flesh what pertains to the flesh.'

The Tome was initially rejected at the 'Robber Council' of Ephesus in 449, where Eutyches was rehabilitated and his opponents deposed by force. But the Council of Chalcedon in 451 reversed this verdict and adopted Leo's Christological formula. When the Tome was read aloud, the bishops famously declared: 'Peter has spoken through Leo.'

Leo's political interventions were equally dramatic. In 452, when Attila's Huns invaded Italy and seemed poised to sack Rome, Leo met the Hunnic king and persuaded him to withdraw — by what combination of diplomacy, bribery, and spiritual authority is debated. Three years later, when the Vandals under Genseric attacked Rome, Leo could not prevent the sacking but negotiated to limit the destruction.

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