The Transfiguration of Christ
Christ - the central figure; He is clothed in white and completely surrounded by a mandorla (body halo) to indicate the brilliant Light of His Divinity which shown from him.
St. Elijah the Prophet - the figure on the Left.
St. Moses the Lawgiver - the figure on the right; he holds in his hands the tablets of the Ten Commandments which he received on Mount Sinai.
The Disciples Peter, James and John - the three figures shown below Christ; they are portrayed in an attitude of being over come by the Uncreated Light of Divinity.
The Transfiguration of Christ is one of the central events recorded in the gospels. Immediately after the Lord was recognized by his disciples as "the Christ, the Son of the Living God," He told them that "He must go up to Jerusalem and suffer many things ... and be killed and on the third day be raised." This announcement of Christ's approaching passion and death was met with indignation by the disciples. And then, after rebuking them, the Lord took Peter, James and John "up to a high mountain," by tradition Mount Tabor, and was "transfigured before them"
In the Transfiguration, the disciples see the glory of the Kingdom of God present in majesty in the person of Christ. They see that in Him, "all the fullness of God was pleased to dwell." They see this before the crucifixion so that in the resurrection they might know who it is who has suffered for them, and what it is that this one, who is Good, has prepared for those who love Him.
Besides this meaning, the presence of Moses and Elijah is also of great significance for understanding the feast. These two figures actually stand for the Old Testament itself: Moses for the Law, and Elijah for the Prophets. They also stand for the Living and the Dead, for Moses died and his burial place is known, while Elijah was taken alive into heaven in order to appear again to announce the time of God's salvation in Christ the Messiah, Christ is the Lord of both the living and the dead. (taken from Worship, the Orthodox Faith Vol.II by Fr. Thomas Hopko)
YOU WERE TRANSFIGURED ON THE MOUNT, O CHRIST GOD, REVEALING YOUR GLORY TO YOUR DISCIPLES AS FAR AS THEY COULD BEAR IT. LET YOUR EVERLASTING LIGHT SHINE UPON US SINNERS! THROUGH THE PRAYERS OF THE THEOTOKOS, GIVER OF LIGHT, GLORY TO YOU!
ON THE MOUNTAIN WERE YOU TRANSFIGURED, O CHRIST GOD, AND YOUR DISCIPLES BEHELD YOUR GLORY AS FAR AS THEY COULD SEE IT; SO THAT WHEN THEY WOULD BEHOLD YOU CRUCIFIED, THEY WOULD UNDERSTAND THAT YOUR SUFFERING WAS VOLUNTARY, AND WOULD PROCLAIM TO THE WORLD, THAT YOU ARE TRULY THE RADIANCE OF THE FATHER!