The following comes from Scott Hahn's site:
High on the holy mountain in today’s Gospel, the true identity of Jesus is fully revealed in His transfiguration.
Standing between Moses and the prophet Elijah, Jesus is the bridge that joins the Law of Moses to the prophets and psalms (see Luke 24:24-27). As Moses did, Jesus climbs a mountain with three named friends and beholds God’s glory in a cloud (see Exodus 24:1,9,15). As Elijah did, He hears God’s voice on the mountain (see 1 Kings 19:8-19).
Elijah was prophesied to return as the herald of the messiah and the Lord’s new covenant (see Malachi 3:1,23-24). Jesus is revealed today as that messiah. By His death and resurrection, which He intimates today to the apostles, He makes a new covenant with all creation.
The majestic voice declares Jesus to be God’s own beloved Son, in whom the Father is well pleased (see Psalm 2:7). God here gives us a glimpse of His inner life. In the cloud of the Holy Spirit, the Father reveals His love for the Son, and invites us to share in that love, as His beloved sons and daughters.
Shadowed by the clouds of heaven, His clothes dazzling white, Jesus is the Son of Man whom Daniel foresees being enthroned in today’s First Reading.
He is the king, the Lord of all the earth, as we sing in today’s Psalm. But is He truly the Lord of our hearts and minds?
The last word God speaks from heaven today is a command—“Listen to Him” (see Deuteronomy 18:15-19). The word of the Lord should be like a lamp shining in the darkness of our days, as Peter tells us in today’s First Reading.
How well are we listening? Do we attend to His word each day?
Let us today rededicate ourselves to listening. Let us hear Him as the word of life, the bright morning star of divine life waiting to arise in our hearts (see Revelation 2:28; 22:16).