Why did Jesus privilege Peter, James, and John at the Transfiguration?

August 6^th, Feast of the Transfiguration of the Lord

And after six days Jesus taketh unto him Peter and James, and John his brother, and bringeth them up into a high mountain apart: And he was transfigured before them. (Matthew 17:1-2)

Christ did not manifest his glory to all peoples at once, nor even did he show himself transfigured to the entire company of the Apostles; rather, he chose only the three – Peter, James the Greater, and John the Beloved – as witnesses to his Transfiguration.

Why, then, was the mystery shared only with these three? Indeed, why are these three regularly favored by our Savior?

Rather than to angels

It was fitting that Peter, James, and John be witnesses to the Transfiguration before even the angels. And this on two accounts.

(1) It was necessary that some from among the followers of Christ, especially from among his Apostles, should be present in order testify to the truth of his glory: And the Word was made flesh, and dwelt among us, (and we saw his glory, the glory as it were of the only begotten of the Father,) full of grace and truth. (John 1:14) According to the words, in the mouth of two or three witnesses.

(2) “By His Transfiguration Christ manifested to His disciples the glory of His body, which belongs to men only. It was therefore fitting that He should choose men and not angels as witnesses.” (Summa Theologica III, q.45, a.3, ad 1)

 Rather than to all the Apostles at once

Moreover, it was fitting that Peter, James, and John should be selected from among the rest since the highest mysteries ought not to be given to all immediately, but rather are best transmitted to all through the superiors. Thus it was that the multiplied loaves were not immediately distributed to the people by Christ, but were given through the mediation of the Apostles. How much more is this mediation necessary when we come to the great mystery of the Transfiguration!

What made Peter, James, and John so special

Peter was greater than the rest on account of the excellence of the love which he had for the Savior: Jesus saith to Simon Peter: Simon son of John, lovest thou me more than these? He saith to him: Yea, Lord, thou knowest that I love thee. He saith to him: Feed my lambs. (John 21:15) Indeed, Peter loved the Lord more than any of the other Apostles, so St. Augustine in his final tractate on John.

Likewise, it was fitting that Peter should be selected from among the rest since he had only just been established as the Prince of the Apostles and the Rock upon which Christ would establish his Church (cf. Matthew 16:18).

James the Greater was chosen by our Savior on account of the privilege he would obtain in being the first of the Apostles to gain the palm of martyrdom.

Finally, John the Beloved was so chosen on account both of our Savior’s particular love which he bore for the Evangelist, and on account of his virginity. Likewise, it was fitting that he who would remain at the foot of the Cross and receive the mother of our Lord as his own mother, should be strengthened for this trial by witnessing the Transfiguration.

Summa Theologica III, q.45, a.3, ad 4

Lofty mysteries should not be immediately explained to everyone, but should be handed down through superiors to others in their proper turn. Consequently, as Chrysostom says (on Matthew 17:3), “He took these three as being superior to the rest.” For “Peter excelled in the love” he bore to Christ and in the power bestowed on him; John in the privilege of Christ's love for him on account of his virginity, and, again, on account of his being privileged to be an Evangelist; James on account of the privilege of martyrdom. Nevertheless He did not wish them to tell others what they had seen before His Resurrection; “lest,” as Jerome says on Matthew 17:19, “such a wonderful thing should seem incredible to them; and lest, after hearing of so great glory, they should be scandalized at the Cross” that followed; or, again, “lest [the Cross] should be entirely hindered by the people” [Bede, Hom. xviii; cf. Catena Aurea]; and “in order that they might then be witnesses of spiritual things when they should be filled with the Holy Ghost” [Hilary, in Matth. xvii].