The transfiguration is one of the most profound mysteries, here we have Moses who represents the law of God, present with Elijah who represents the prophets of God. Jesus leads Peter, James, and John his brother up a high mountain, just like Moses and Elijah got a revelation from God up a mountain. Whats interesting is Jesus is transfigured before them all. Its Moses and Elijah conversing with Jesus, As they did in their history Moses speaking with God in the Burning Bush, and in the meeting tent, not to mention when Moses ask to see God, Moses being hidden between the rocks and God passed revealing only the back tail of his glory, and Elijah who doesnt find God in the fire or earthquake but in the wispering wind. A point to make here is Moses said a prophet like me will be sent to you and you will listen to him, Elijah is the one who is to announce the coming of the Lord, the Messiah. All this is made present in a single moment before eyewitnesses and much more… Now God speaks from the cloud and says " This is my beloved Son, with whom Iam well pleased" whats mysterious is that Moses and Elijah dissappear and only Jesus is there, Jesus is the fulfillment of the law and the prophets. And God says to the Apostles with the law giver gone and the prophet, “LISTEN TO HIM”, just like his mother stated in the wedding at cana, to the servers the Blessed Mother said, “DO WHATEVER HE TELLS YOU”. The mysteries are endless upon meditating and contemplating them. God is God of the living not the dead.