The traditional site of the Transfiguration is Mount Tabor. I saw it on a trip to Israel. It stands like a strange lump on the Jezreel Valley not far from Nazareth. It is not a huge mountain (approximately 1800ft tall), but it would be enough to create some separation between an event at the summit and the sleeping populace below. The event is described in Matthew 17, Mark 9, and Luke 9. It was witnessed by Peter, James, and James brother John. Why John doesn’t include it in his Gospel is a bit of a mystery. Perhaps he is taking Jesus’ warning to not talk about the event until after His resurrection a bit further. Peter talks about it in 2 Peter 2.
Since Mark is thought to depend on Peter, here is his account:
And after six days Jesus took with him Peter and James and John, and led them up a high mountain by themselves. And he was transfigured before them, 3 and his clothes became radiant, intensely white, as no one on earth could bleach them. 4 And there appeared to them Elijah with Moses, and they were talking with Jesus. 5 And Peter said to Jesus, “Rabbi, it is good that we are here. Let us make three tents, one for you and one for Moses and one for Elijah.” 6 For he did not know what to say, for they were terrified. 7 And a cloud overshadowed them, and a voice came out of the cloud, “This is my beloved Son; listen to him.” 8 And suddenly, looking around, they no longer saw anyone with them but Jesus only.
9 And as they were coming down the mountain, he charged them to tell no one what they had seen, until the Son of Man had risen from the dead. 10 So they kept the matter to themselves, questioning what this rising from the dead might mean. 11 And they asked him, “Why do the scribes say that first Elijah must come?” 12 And he said to them, “Elijah does come first to restore all things. And how is it written of the Son of Man that he should suffer many things and be treated with contempt?Mark 9:2-12 (ESV)
The event clearly seems important, yet no explanation is given by anyone as to why it happened or what it did. This is one of the most intriguing things about it.
Jesus takes just three. They are His inner circle, and since the event is meant to be secret for the time being a small number makes sense. They are given no warning and it is early enough that no one notes their departure. One account notes that they are sleepy. It is hard to imagine that someone would not be fully awake after climbing an 1800-foot hill. I think the sleepiness has something to do with the spiritual interface they were about to experience.
Moses and Elijah appear. I have no idea how the disciples would know who they are. This doesn’t seem like a mixer with introductions or name tags. They just know. Why are these men there? First, we should note where they had been. Moses is dead about 1500 years. Elijah more like 600. They have not come from Heaven. Jesus clearly says that no human has been there except Him (John 3:11). These men were in Sheol https://afterdeathsite.com/2021/05/11/an-expectation-of-sheol/. They represent all of the Old Testament righteous who have been waiting patiently for the atonement for sins that Jesus would accomplish. Jesus’ success matters for them, and they are honored to see this moment and to be encouragement.
Jesus Himself needs strength. Do not think that the victory over Satan and sin was either easy or a foregone conclusion. Jesus knows who He is and what He has come to do. His transfiguring brings forward an aspect of His divine nature for a moment. I doubt that it was merely for show. Jesus needed this, whatever it was, so would Peter, James and John and those they would support. The crucifixion would seem to be wrong. It would look like a failure. It didn’t fit in anybody’s preconceived notions of what the Messiah should do. We only have to look at how Peter himself wobbled by denying Jesus three times.
The pinnacle of the event would be the arrival of the Father in shrouded glory. The Father had spoken before at Jesus’ baptism. No physical manifestation happened at that time beyond the Holy Spirit appearing as a dove. Here the glory of God is shrouded from the humans on the peak. Why? Humans in their natural sinful form cannot tolerate the direct glory of God. Moses was shielded in the cleft of a rock and could not see God’s face. Moses, Nadab and Abihu with the 70 elders of Israel saw God but through the filter of God’s floor. Daniel and Isaiah had visions but not direct contact. It would remain so here. Just to be safe Peter, James and John hit the dirt.
Finally, the event is over and Jesus asks for silence about it. The presence of Elijah had caught the disciples’ attention. They had heard about Elijah’s return and had practiced it with an empty seat at the Passover table. The reason for this expectation is the last passage of the Old Testament:
5 “Behold, I will send you Elijah the prophet before the great and awesome day of the Lord comes. 6 And he will turn the hearts of fathers to their children and the hearts of children to their fathers, lest I come and strike the land with a decree of utter destruction.”Malachi 4:5-6 (ESV)
It is curious that the disciples ask about Elijah. Previously, in Matthew 11:14, Jesus had identified John the Baptist as the “Elijah who was to come”. But it is possible that Jesus’ disciples were not there for that speech. What was Elijah/John the Baptist supposed to restore? A general heart of repentance and readiness for a Messiah that would atone for sins. One could interpret this mission as largely a failure. God does strike Israel with the destruction of the Temple and eventual dispersion.