Two postings back, I happened to mention a Spaso-Preobrazhenskiy Monastery — a “Savior-Transfiguration Monastery.” And that moved one of my readers to write me a note saying I did not seem to have done a page on the Transfiguration. Well, apparently she is correct, though I did mention it briefly in a discussion of icons of the major Church festivals.
So here it is — a Russian example of the Transfiguration type from 1497:

The title inscription is a bit worn, but it appears to read:
ПРЕѠБРАЖЕНИЕ ГОСПОДА НАШЕГО ИСУСА ХРИСТА
PREOBRAZHENIE GOSPODA NASHEGO ISUSA KHRISTA
“TRANSFIGURATION OF OUR LORD JESUS CHRIST”
The story of the Transfiguration of Jesus is found in the Synoptic Gospels, with both “Matthew” (17:1-8) and “Luke” (9:28-36) apparently basing their accounts on that of “Mark” 9:2-9:
And after six days Jesus takes with him Peter, and James, and John, and leads them up into an high mountain apart by themselves: and he was transfigured before them.
3 And his clothing became shining, exceeding white as snow; so as no fuller on earth can whiten them.
4 And there appeared to them Elijah with Moses: and they were talking with Jesus.
5 And Peter answered and said to Jesus, Master, it is good for us to be here: and let us make three tabernacles; one for you, and one for Moses, and one for Elijah.
6 For he knew not what to say; for they were very afraid.
7 And there was a cloud that overshadowed them: and a voice came out of the cloud, saying, This is my beloved Son: hear him.
8 And suddenly, when they had looked round about, they saw no man any more, except Jesus only with themselves.
9 And as they came down from the mountain, he commanded them that they should tell no man what things they had seen, till the Son of man was risen from the dead.
It is possible that the author of “Mark” intended the appearance of Moses and Elijah with Jesus to reflect Malachi 4:4-5:
Now Mark had merely said the three were “very afraid,” so this dramatic falling to the ground is a detail added to Mark’s story by Matthew in 17:6:
6 And when the disciples heard it, they fell on their faces, and were very afraid.
“Luke” says nothing about falling to the ground, but does add another detail of his own (Luke 9:32) not mentioned in Mark or Matthew:
32 But Peter and they that were with him were heavy with sleep: and when they were awake, they saw his glory, and the two men that stood with him.
Now in Eastern Orthodoxy, the Transfiguration came to have a special significance due to a doctrine found in the writings of Gregory Palamas (1296-1359), who defended the notion of Hesychasm. In Hesychasm, it is believed that a person through meditative practice may become so purified that a union with God happens, and in that union a bright divine light is seen, which is considered to be the same light as that of the Transfiguration of Jesus. This “uncreated light” is therefore called in Russian the Фаворский свет/Faborskiy svyet/ “Light of Tabor,” and in Greek the Ἄκτιστον Φῶς/Aktiston Phos (“Uncreated Light”) or Θεῖον Φῶς/Theion Phos (“Divine Light”).
Now it is common knowledge in the study of meditative practices — and particularly noted in Buddhism — that certain types of meditation can lead to the experience of light, though that result is not given the interpretation found in Hesychasm, but is rather just considered a stage on the meditative journey. The doctrine of Hesychasm was very controversial in Eastern Orthodoxy, but was eventually accepted — though it was not found in Roman Catholicism and certainly not in Protestantism.
As an example of the Eastern Orthodox attitude toward this light, we may look to the account found in what are said to be the memoirs of Nikolay/Nicholas Motovilov (1809-1879) —

memoirs discovered, so the story goes, in a pile of rubbish in 1902. The account relates Motovilov’s conversation with the ascetic St. Seraphim of Sarov (1754-1833):
“Nevertheless,” I replied, “I do not understand how I can be certain that I am in the Spirit of God. How can I discern for myself His true manifestation in me?”
Father Seraphim replied: “I have already told you, your Godliness, that it is very simple and I have related in detail how people come to be in the Spirit of God and how we can recognize His presence in us. So what do you want, my son?”
“I want to understand it well,” I said.
Then Father Seraphim took me very firmly by the shoulders and said: “We are both in the Spirit of God now, my son. Why don’t you look at me?”
I replied: “I cannot look, Father, because your eyes are flashing like lightning. Your face has become brighter than the sun, and my eyes ache with pain.”
Father Seraphim said: “Don’t be alarmed, your Godliness! Now you yourself have become as bright as I am. You are now in the fullness of the Spirit of God yourself; otherwise you would not be able to see me as I am.”
Then, bending his head towards me, he whispered softly in my ear: “Thank the Lord God for His unutterable mercy to us! You saw that I did not even cross myself; and only in my heart I prayed mentally to the Lord God and said within myself: ‘Lord, grant him to see clearly with his bodily eyes that descent of Thy Spirit which Thou grantest to Thy servants when Thou art pleased to appear in the light of Thy magnificent glory.’ And you see, my son, the Lord instantly fulfilled the humble prayer of poor Seraphim. How then shall we not thank Him for this unspeakable gift to us both? Even to the greatest hermits, my son, the Lord God does not always show His mercy in this way. This grace of God, like a loving mother, has been pleased to comfort your contrite heart at the intercession of the Mother of God herself. But why, my son, do you not look me in the eyes? Just look, and don’t be afraid! The Lord is with us!”
After these words I glanced at his face and there came over me an even greater reverent awe. Imagine in the center of the sun, in the dazzling light of its midday rays, the face of a man talking to you. You see the movement of his lips and the changing expression of his eyes, you hear his voice, you feel someone holding your shoulders; yet you do not see his hands, you do not even see yourself or his figure, but only a blinding light spreading far around for several yards and illumining with its glaring sheen both the snow-blanket which covered the forest glade and the snow-flakes which besprinkled me and the great Elder. You can imagine the state I was in!
“How do you feel now?” Father Seraphim asked me.
“Extraordinarily well,” I said.
“But in what way? How exactly do you feel well?”
I answered: “I feel such calmness and peace in my soul that no words can express it.”
And of course there is the bright light mentioned in many accounts of “near-death” experiences.
Greek icons of the Transfiguration like that below usually have the title Ἡ ΜΕΤΑΜΟΡΦѠCΙC/HE METAMORPHOSIS/”THE TRANSFIGURATION,” or some variant of it.
Note the damaged area at lower center, where paint loss has revealed the underlying fabric.
Here is a more elaborate 1600 example:
Jesus at center holds the Gospels, Elijah is at left, and at right is Moses, holding the tablets of the Law.
At lower left we see Jesus leading Peter, James and John up Mount Tabor —
And at lower right he speaks to them after the Transfiguration:
And here is a closer look at the central image of Jesus:
Now we have seen that Russians call the “Uncreated Light” the “Light of Tabor” — of Mount Tabor, that is. But oddly enough the mountain is not identified at all in the Gospels. They just call it a “high mountain” (Mark and Matthew), and “a mountain” (Luke). And it is not until the 3rd century that we find it named in the writings of Origin as Mount Tabor.