The Transfiguration foretells the glory of the Lord as God, and His Ascension into heaven .It anticipates the glory of heaven, where we shall see God face to face. Through grace, we already share in the divine promise of eternal life.
We pray :
God our Father, in the transfigured glory of Christ Your Son, You strengthen our faith by confirming the witness of Your prophets, and show us the splendor of Your beloved sons and daughters. As we listen to the voice of Your Son, help us to become heirs to eternal life with Him who lives and reigns with You and the Holy Spirit, one God, for ever and ever. Amen.
Jesus and the three apostles -- Peter, James and John -- went up to the top of Mount Tabor. At a certain moment the Divine Master disappeared from their sight to reappear all at once in a glory of light and splendor. Moses and Elijah stood on either side of him, and Jesus was talking to them. Moses represented the Law, Elijah the prophecies that had been made through the centuries, foretelling the Redemption of man. What was Jesus speaking about with these two personages of the Old Testament? Certainly not about human and worldly opinions and enterprises, nor about the enjoyment of this transient life, but about the fulfillment of the purpose of God's infinite goodness, in accordance with which the Son of God made man was about to suffer and die on the Cross in order to save mankind.
The three apostles were not yet capable of understanding all this; they were so entranced by the vision that they wished it could last forever, so intense was the joy of their hearts. Stricken with awe they fell to the ground, but were soon raised again by Jesus who had re-assumed His ordinary human appearance. "Rise, and have no fear." That was the first order He gave them, and then, as they were coming down from the mountain, He said: "Tell no one the vision, until the Son of Man is raised from the dead."
In this episode described by St Matthew there is a profound and sublime lesson for all times, and for Christians of all sorts and conditions. In this earthly life we must not expect every hour to offer us joy, pleasures and glory, even if we seek these with an honest and legitimate purpose.
( — Pope John XXIII )