Saint Pope Leo I (born in the 4th century) served as pope from 440 to 461 and stands as a master exponent of papal supremacy.
His entire pontificate was devoted to safeguarding Christian orthodoxy and securing the unity of the Western Church under the leadership of the Roman See.
He was also called as the Firsts of a Pope. Why? It is because he was the first pope to be called “the Great”, the first pope named Leo, the first pope to have a large collection of his own sermons and letters survive to the present day, and the first pope buried inside the original St. Peter’s Basilica.
His theological letter to Patriarch Flavian of Constantinople (the Tome) clearly defined the hypostatic union that Jesus Christ has two distinct natures (divine and human) united in one person. This letter formed the doctrinal basis for the Council of Chalcedon in 451, where bishops reportedly shouted, “Peter has spoken through Leo!”
Recognizing his immense contribution to Christian doctrine and theology, Pope Benedict XIV officially named him a Doctor of the Church in 1754.
Saint Leo the Great, pray for us!