This icon is a part of a celebrated set of festal icons showing important events in the life of Jesus plus a few other renowned feasts of the year.
The Transfiguration is considered a very important feast in Eastern Orthodox Christianity because it is the first true revelation of the brightness of the Light of Christ in this world to His Apostles and to us through them. The Disciples are blinded by this great Light and fall down as Christ becomes much more than just a miracle-working prophet or man, but the Living God before the Ages Whose Glory has been hidden from the Apostles behind the veil of His humanity. On one side of the icon, the Apostles are led up the mountain, and on the other side they are led down, because time is simultaneous in true iconographic art, echoing Eternity entirely present at once. The Holy Prophets Moses and Elias (or Elijah) appear also to affirm that this is truly the God that they saw before.