by Luis E. Lugo

On the Saturday before the second Sunday of Lent in 445, Pope Leo, whose pontificate spanned more than twenty years, preached a powerful sermon on the Transfiguration. It is one of the nearly one hundred sermons that have been preserved from the first bishop of Rome to have been called Leo (twelve others would follow). The sermons hold the distinction of being the first papal homilies that have come down to us that were preached to the people during liturgical celebrations.

This was the same Leo who would earn the title "the Great" because of his many notable accomplishments. One such was his decisive intervention at the Fourth Ecumenical Council, the Council of Chalcedon of 451, which cemented the Christological doctrine of the three previous councils. This came by way of a letter (known as the Tome of Leo) that was read to the hundreds of assembled bishops, who, upon the completion of its reading, acclaimed in unison: "Peter has spoken through the mouth of Leo."

Another memorable episode took place the very next year when Leo was instrumental in preventing the sacking of Rome by Attila the Hun. When the latter entered Italy in 452, he began to sack and burn cities while winding his way to Rome. The frightened Roman population begged Leo to go out and try to persuade the fierce Hun to spare the Eternal City. Leo courageously accepted the challenge, met with Attila, and convinced him to withdraw his forces.

Leo also successfully fought heresies and carried out diplomatic missions, but he was foremost a pastor to his flock. And it's in that capacity that he preached his sermon on the Transfiguration, which he based on Matthew 17:1-13.

Leo sets the context by referring back to the previous chapter in Matthew, specifically to Peter's famous confession of Jesus as the Christ, the Messiah. This Christ, Leo explains, was indeed the only begotten Son of God, but also the Son of Man: "For the one without the other was of no avail to salvation."

Here Leo echoes the words of St. Gregory of Nazianzus, who died shortly before Leo was born. "The Theologian" had referred to Jesus' "thick corporeality" while famously proclaiming that "that [part of man's nature] which is not assumed, is not healed."

Leo argues that "it was equally dangerous to have believed the Lord Jesus Christ to be either only God without manhood, or only man without Godhead." Thus, with one fell swoop, he lays waste the main heresies that had troubled the Church during the prolonged period of Christological controversies.

Although Peter's confession had rightly exalted Christ's higher nature, Leo observes, the apostle needed to be instructed on "the mystery of Christ's lower substance." Peter's imperfect understanding of this mystery is evidenced by his rebuke of Jesus when the latter speaks of his approaching Passion. This reproof makes clear, Leo declares, that although Peter and the other apostles "had recognized the mystery of God in Him, yet the power of His body, wherein His Deity was contained, they did not know."

Leo maintains that the "kingly brilliance" Jesus manifested in the Transfiguration was something as "specially belonging to the nature of His assumed Manhood." It is in his humanity, he contends, that the Lord "displays his glory. . .and invests that bodily shape which He shared with others with such splendor."

The Transfiguration was intended "to remove the offense of the cross from the disciple's heart, and to prevent their faith being disturbed by the humiliation of His voluntary Passion by revealing to them the excellence of His hidden dignity." It is by means of Christ's punishment on the Cross, Leo states, that God "opens the way to heaven" and prepares for us "the steps of ascent to the Kingdom."

Jesus' transfigured body reveals the nature of that Kingdom and the culmination of salvation history. In fact, Leo is of the view that Jesus' promise that certain of his disciples standing by Him would not taste death until they saw th...