At the Transfiguration, Moses represented the law and Elijah represented the prophets. But why were Peter, James, and John present? And what does this event mean to us today?
St. Thomas Aquinas devotes an entire section in his Summa theologiae to the Transfiguration. His treatment offers some answers.
Aquinas says that it was fitting that Christ be manifested in his glory because those who are walking an arduous path need a clear sense of the goal of their journey. The arduous path is this life, with all of its attendant sufferings, failures, setbacks, disappointments, and injustices. And its goal is heavenly glory, which is fullness of life with God, the transformation of our bodies.
As Jesus makes his way toward the cross, he accordingly allows, for a brief time, his glory to shine through, the radiance of his divinity to appear. This event is meant to awaken our sense of wonder and affirm that we are not meant finally for this world.
Next, Aquinas asks about the “light” or the “glory” that envelops Christ during the Transfiguration, noting that it “shines.” Why have people, trans-historically and trans-culturally, associated holiness with light? Well, light is that by which we see, that which illumines and clarifies. But light is also beautiful, and beautiful things shine. Aquinas says that Jesus, at the Transfiguration, began to shine with the radiance of heaven so as to entrance us with the prospect of our own transfiguration.
Finally, Aquinas talks about the “witnesses” to the Transfiguration, namely Peter, James, John, Moses, and Elijah. Moses stands for the Law, and Jesus recapitulates, perfects, and illumines the Mosaic law: “I have come not to abolish the law but to fulfill it.” Christ is the new Moses, the new Lawgiver.
Similarly, Elijah stands for the prophets; he was the greatest of the prophets. The prophets spoke the words of God. And since Jesus is the Word of God, the prophetic books are read in his light.
So why is Peter there? Because, says Aquinas, he loved the Lord the most. Why is John there? Because the Lord loved him the most. Why is James there? Because he was the first of the Apostles to die for his faith. Who gets access to the glory of Jesus? Those who are tied to him through love.