Saint Saint Leo the Great, Pope and Doctor

Pope Leo I (Italian: Leone I) (c. 391 – 10 November 461), also known as Leo the Great (Latin: Leo Magnus; Italian: Leone Magno), was Bishop of Rome from 29 September 440 until his death on 10 November 461. He is the first of the three Popes listed in the Annuario Pontificio with the title "the Great", alongside Popes Gregory I and Nicholas I. Leo was a Roman aristocrat. He is perhaps best known for meeting Attila the Hun in 452 and persuading him to turn back from his invasion of Italy, though how large a part his personal authority played is debated, and some argue that Attila was already ready to end his campaign. He is also a Doctor of the Church, most remembered theologically for issuing the Tome of Leo, a document which was a major foundation to the debates of the Council of Chalcedon, the fourth ecumenical council. That meeting dealt primarily with Christology and elucidated the definition of Christ's being as the hypostatic union of two natures, divine and human, united in one person, "with neither confusion nor division". It was followed by a major schism associated with Monophysitism, Miaphysitism and Dyophysitism. He also contributed significantly to developing ideas of papal authority. According to the Liber Pontificalis, he was a native of Tuscany and son of Quintianus or Quintilianus. By 431, as a deacon, he was sufficiently well known outside of Rome that John Cassian dedicated to him the treatise against Nestorius written at Leo's suggestion. About this time Cyril of Alexandria appealed to Rome regarding a jurisdictional dispute with Juvenal of Jerusalem, but it is not entirely clear whether the letter was intended for Leo in his capacity as archdeacon, or for Pope Celestine I directly. Near the end of the reign of Pope Sixtus III, Leo was dispatched at the will of Emperor Valentinian III to settle a dispute between Aëtius, one of the chief Roman military commanders in Gaul, and the chief magistrate Albinus.