Fr. John Zuhlsdorf
If you want to know what happened in the transfiguration start by reading Matthew 17, Luke 9 and Mark 9. John does not recount it. We also hear about it in 2 Peter 1:16-18. It harkens to the description of the Ancient of Days in Daniel 7.
We need to place this in some sort of context. Jesus and the apostles are on their way to Jerusalem for the last time and Christ will soon be crucified. The Transfiguration takes place about a week after Peter makes his profession at Caesarea Philippi and calls Jesus the Messiah. Jesus entrusts the “keys” to Peter and tells him that he will be the Rock, the foundation of His Church. Jesus told them about his upcoming Passion. Peter remonstrated with him and Jesus slaps him down hard. Now they are at the mountain. A few of them go apart with Jesus up the mountain.
Jesus knows what is going to happen in Jerusalem. He knows what impact it will have on the men who follow him. So, he forewarns them and strengthens them in their faith in him. This is not for Peter’s sake only, though Christ knows that when he comes to his senses it will be he who must “strengthen the brethren.” He does this also for two other supports of the early Church, John and James (cf. Gal. 2:9). The glimpse of glory they receive will help them through what is coming just ahead. At this moment, the Father testifies to Christ just as he did at Jesus’s baptism (Cf. Matt. 3:17). The Father also says “Listen to him,” which connects Jesus to Moses in Deut. 18:15-18.
At that moment, the divine glory of Christ’s divinity, to that point in his life always veiled and hidden in humility and self-emptying, shone out and transfigured/glorified for a moment his human body. This is not his glorified body: the triumph of the resurrection had not yet been completed. This is something else completely. This is a confirmation of his divinity and equality with the Father. It is a promise of future glory to us who belong to him. It is a ratification of what he has already done in his ministry (especially, in my opinion, what he gave to Peter just before) and what he was about to do in Jerusalem: reject earthly power and endure his Passion for our sake and do give the Father glory.
Here are a few ideas about this incredible mystery of the Lord.
First, and in no special order, some suggest that the Transfiguration marks a transition from Jesus as acting in a prophetic mode to him acting in a priestly mode. He is now on his way to be the ultimate Victim Priest. So, as the epiphany of his divinity marked his baptism and the beginning of the prophetic stage, another epiphany and “anointing” by the Father marks his priestly stage.
Moses and Elijah are there. They represent the Law and Prophets. Christ is central, which is the position of superiority. Christ is being revealed as God in this moment, so we understand that all that Moses and Elijah did, great as it was, was given to them by the one between them. And what they did was nothing compared to what Christ was going to do. Christ is indicating that the entirety of the Old Covenant was about to be transformed in his own passion, death, and resurrection.
The fact that the Confession of Peter was the preparatory event before the Transfiguration shows us something about the Church. Having taken up our human nature, Christ unites all men in his divine person. We are all with him in the human nature he has taken up. If Emanuel is “God with us,” we are now “man with him.” We have a communion of nature with him and in him. This communion of nature calls for common faith in Christ, obedience to his authority and those to whom he gives his own authority, and communion in the sacraments he gave. The Church, as St. Hilary of Poitiers would say, is the “glorious Body of Christ” and brings to completion in a sense the work begun in the Incarnation. Peter receives his mission as a prelude to the revelation of Christ’s transforming divine glory. At the Last Supper (where Jesus is now about to go soon) has Jesus praying that all “be one,” he establishes his priesthood, and he confirms that Peter is the one to “strengthen the brethren.” “Listen to him” leads to “He who hears you hears me.” Peter is the “key” to this.
Our humanity is revealed as the vessel of God’s transforming glory. When God spoke to Moses, he too cast himself on the ground, unable to bear the Lord. When Moses would speak to God, he afterward wore a veil over his face, which still radiated light after the event. The glory of God transforms those whom it touches. And it is destined for the human body. In contrast to Christ’s humility and lowliness (by which he manifests certain things about his divinity), he now is revealed in something more like his true divine splendor, destined for us who belong to him.
Before they could see the transfiguration of the living human flesh of Christ on the mountain, they had to climb the mountain. They went apart, away from the crowds, in to a high place of prayer and contemplation. After the transfiguration they had to go down again, back to the crowds. St. Augustine takes this to indicate how we move from contemplation to action. As the disciples did not see Christ’s divine splendor before this moment, Christ was nevertheless who he was. His eternal glory was hidden from their eyes. Christ’s divine splendor is hidden from our eyes also in the flesh of the poor, the sick, the lame, the dying, the impaired. Their flesh was transfigured by Christ on the mount. As Christ is resplendent in transforming divine glory now, they too await a transfiguration, even if their future glory is hidden from our earthly eyes. Christ said: “Whatever you do to the least of these, you did to me.” In our solidarity with Christ, in the Church, we must seek the mountain top and at the same time come down from the mountain top in order to fulfil the pattern of transformation that Christ set down for us. This is an inexhaustible mystery. These are a few poor crumbs.