Leo I was a son of Tuscany who was elected pope in 440. Though unable to attend the Council of Chalcedon in 451, his letter (or Tome) defining Christ’s twofold nature was acclaimed as the Church’s teaching: “Peter has spoken through Leo.” His famous meeting with Attila the Hun outside Rome the following year (452) saved the city from destruction then, although, despite his efforts, it was pillaged by Vandals in 455. Leo died in 461. His theological writings earned him the title of Doctor of the Church. – CTS New Daily Roman Missal 2012, p 3134
