known as Leo the Great
born 4th century, Tuscany?
died Nov. 10, 461, Rome; Western feast day November 10, Eastern feast day February 18
Pope (440–461).
He was a champion of orthodoxy and a Doctor of the Church. When the monk Eutyches of Constantinople asserted that Jesus Christ had only a single divine nature, Leo wrote the Tome, which established the coexistence of Christ's human and divine natures. Leo's teachings were embraced by the Council of Chalcedon (451), which also accepted his teaching as the "voice of Peter." Leo dealt capably with the invasions of barbaric tribes, persuading the Huns not to attack Rome (452) and the Vandals not to sack the city (455). Leo was also an exponent of the precept of papal primacy, and his personal example and letters and sermons contributed greatly to the growth of papal authority.