Jesus had gone with his disciples Peter, James, and John to Mount Tabor. Christ's appearance was changed while they watched into a glorious radiant figure. There appeared Elijah and Moses, speaking with Jesus. The disciples were amazed and terribly afraid.
This event shows forth the divinity of Christ, so that the disciples would understand after his Ascension that He was truly the radiant splendor of the Father, and that his Passion was voluntary (Gospel of Mark 9:2-9).