Jesus had a transformation experience on a mountain when His face shone like the sun and His clothing became dazzling white (Mt 17:1-13). This phenomenon came from within and was not a reflection from some external light source.
This complete change in visible appearance was a special revelation to three of the disciples (Peter, James, John) that Jesus was truly God’s son. It was also God’s confirmation of everything He had done and was yet to do, and a foretaste of the radiant, divine glory and majesty Christ will have in eternity (Rev 5:12,13). The presence of Moses and Elijah (representing the law and prophets) with the supernatural testimony from heaven showed how superior Christ was to these forerunners.
See also: transform/transformation.