CCC 554 From the day Peter confessed that Jesus is the Christ, the Son of the living God, the Master “began to show his disciples that he must go to Jerusalem and suffer many things. .. and be killed, and on the third day be raised.”1 Peter scorns this prediction, nor do the others understand it any better than he.2 In this context the mysterious episode of Jesus’ Transfiguration takes place on a high mountain,3 before three witnesses chosen by himself: Peter, James and John. Jesus’ face and clothes become dazzling with light, and Moses and Elijah appear, speaking “of his departure, which he was to accomplish at Jerusalem”.4 A cloud covers him and a voice from heaven says: “This is my Son, my Chosen; listen to him!”5
CCC 555 For a moment Jesus discloses his divine glory, confirming Peter’s confession. He also reveals that he will have to go by the way of the cross at Jerusalem in order to “enter into his glory”.6 Moses and Elijah had seen God’s glory on the Mountain; the Law and the Prophets had announced the Messiah’s sufferings.7 Christ’s Passion is the will of the Father: the Son acts as God’s servant;8 the cloud indicates the presence of the Holy Spirit. “The whole Trinity appeared: the Father in the voice; the Son in the man; the Spirit in the shining cloud.”9
You were transfigured on the mountain, and your disciples, as much as they were capable of it, beheld your glory, O Christ our God, so that when they should see you crucified they would understand that your Passion was voluntary, and proclaim to the world that you truly are the splendor of the Father.10
1 Mt 16:21.
2 Cf. Mt 16:22-23; 17:23; Lk 9:45.
3 Cf. Mt 17:1-8 and parallels; 2 Pt 1:16-18.
4 Lk 9:31.
5 Lk 9:35.
6 Lk 24:26.
7 Cf. Lk 24:27.
8 Cf. Is 42:1.
9 St. Thomas Aquinas, STh III, 45, 4, ad 2.
10 Byzantine Liturgy, Feast of the Transfiguration, Kontakion.