“And as he prayed, the appearance of his countenance was changed, and his raiment became a radiant white” (Lk. 9, 28).
In brush strokes:
- The Transfiguration in the gospel of Luke (9, 28): “…he took Peter, James and John and went up the mountain to pray. And as he prayed, the appearance of his countenance was changed, and his raiment became a radiant white.”
- Ratzinger commented: “In the Gospels, ‘the mountain’ is always the realm of prayer, of being with the Father. It was to this ‘mountain’ that Jesus had taken the Three who formed the core of the community of the Twelve: Peter, James and John. ‘As he was praying, the appearance of his countenance was altered,’ Luke tells us.”
- What is the meaning of the act of praying? Ratzinger uses this quote, as well as Lk. 6, 12 and Lk. 9, 18 to maintain that the Person of Christ – Who is the Son of the Father, and therefore totally and purely relational as divine Person – is showing who He is by the acting praying, which is the supreme relational act through His human nature.
- Thomas has given a metaphysical account of the divine Persons as ipsum esse subsistens where esse is “the act of all acts, perfection of all perfections” [Summa Theologiae 1, 4, 1 ad 3d] in view of all creation. As a result, if created beings “are,” “Ipsum esse” is not since “Ipsum esse” is the Creator that is even if all of creation were not. And, it must be possible for creation to have not been, since it was nothing “before” being created.
- The result of this revelation of creation from nothing is the different way of knowing God from the way we know creation. God is pure activity as Person of Father engendering Son, Son glorifying Father and Spirit as Personification of both. The beings of Creation are always individuals who are this and that The Creator, on the other hand, is such that it is not possible to know One Divine Person without knowing the Others. The action that each One is implies the reality of the Other. Hence, by our intramundane sensible way of knowing, we can know that God exists, but we cannot know the Persons in themselves as dynamic activities of Father, Son and Spirit. This only comes when That Father reveals Himself in the Son with the Spirit. St. John testified that “no one has at any time seen God. The only begotten Son, who is in the bosom of the Father, he has revealed him” (Jn. 1 , 18), and Jesus Himself testified that “No knows the Don except the Father; nor does anyoneknow the Father except the Son, and him to whom the Son chooses to reveal him” (Mt. 11, 27).
- Therefore, the question Christ puts to Simon: “Who do men say that I am?” is so critical. The context of the question is the participation of Simon and the other Apostles in the prayer of Christ (Lk. 9, 18). Participating in that prayer means that they were going forth from themselves to the Father as Christ was the going forth from self to the Father. They experienced something in themselves that Christ experienced in Himself as God-man and Son of the Father. That is, they experienced being “like” Christ to some degree. And hence, Simon was able to say: “You are the Christ, the Son of the living God” (Mt. 16, 16) because he experienced in himself what Christ experienced in Himself. And so, he was able to transfer the name “Christ” to the Jesus Who prayed beside him about whom he perceived the name and reality in himself. To which Christ replied: “Flesh and blood has not revealed this to you, but my Father who is in heaven” (Mt. 16, 17). That knowledge does not come from creation, but from within the experience Simon has of himself.
- Hence, Christ is transfigured as God of Light because His divine “I” He activated His human will to do what He is: to be Relation to the Father in the form of prayer.
 J. Ratzinger, “Behold the Pierced One,” Ignatius (1986) 20.
 Christ calls “Peter” (Rock) because Rock is “like” the cornerstone who Christ is (cf. Isaiah 22, 22).