+ Mk 9: 2-13
After six days Jesus took Peter, James, and John and led them up a high mountain apart by themselves. And he was transfigured before them,
and his clothes became dazzling white, such as no fuller on earth could bleach them.
Then Elijah appeared to them along with Moses, and they were conversing with Jesus.
Then Peter said to Jesus in reply, “Rabbi, it is good that we are here! Let us make three tents: one for you, one for Moses, and one for Elijah.”
He hardly knew what to say, they were so terrified.
Then a cloud came, casting a shadow over them; then from the cloud came a voice, “This is my beloved Son. Listen to him.”
Suddenly, looking around, they no longer saw anyone but Jesus alone with them.
As they were coming down from the mountain, he charged them not to relate what they had seen to anyone, except when the Son of Man had risen from the dead.
So they kept the matter to themselves, questioning what rising from the dead meant.
Then they asked him, “Why do the scribes say that Elijah must come first?”
He told them, “Elijah will indeed come first and restore all things, yet how is it written regarding the Son of Man that he must suffer greatly and be treated with contempt?
But I tell you that Elijah has come and they did to him whatever they pleased, as it is written of him.”
The New American Bible
The Catechism of the Catholic Church
552 Simon Peter holds the first place in the college of the Twelve; Jesus entrusted a unique mission to him. Through a revelation from the Father, Peter had confessed: “You are the Christ, the Son of the living God.” Our Lord then declared to him: “You are Peter, and on this rock I will build my Church, and the gates of Hades will not prevail against it.” Christ, the “living Stone”, thus assures his Church, built on Peter, of victory over the powers of death. Because of the faith he confessed Peter will remain the unshakable rock of the Church. His mission will be to keep this faith from every lapse and to strengthen his brothers in it.
151 For a Christian, believing in God cannot be separated from believing in the One he sent, his “beloved Son”, in whom the Father is “well pleased”; God tells us to listen to him. The Lord himself said to his disciples: “Believe in God, believe also in me.” We can believe in Jesus Christ because he is himself God, the Word made flesh: “No one has ever seen God; the only Son, who is in the bosom of the Father, he has made him known.” Because he “has seen the Father”, Jesus Christ is the only one who knows him and can reveal him.
459 The Word became flesh to be our model of holiness: “Take my yoke upon you, and learn from me.” “I am the way, and the truth, and the life; no one comes to the Father, but by me.” On the mountain of the Transfiguration, the Father commands: “Listen to him!” Jesus is the model for the Beatitudes and the norm of the new law: “Love one another as I have loved you.” This love implies an effective offering of oneself, after his example.