Pope Leo I

Born into the Roman aristocracy around 391, Leo became Bishop of Rome on 29 September 440. Two years into his papacy, he traveled north to meet Attila as the Hun's forces bore down on Italy; Attila withdrew, and Leo's legend was set, though historians still debate how much was persuasion and how much was Attila's pre-existing intent to pull back. Theologically, he issued the Tome of Leo, a text that became foundational at the Council of Chalcedon in defining Christ as one person in two natures — divine and human, neither confused nor divided. The doctrine triggered a schism that split churches…