In today's gospel we hear,
And he was transfigured before them; his face shone like the sun
But the word for face means much more that the physical face. The word in Mathew's gospel "prosopon" became one of the first points of controversy in Christianity. The word conveys not just your physical face, but your identity, your truest self. Peter, James , and John see clearly, fully, who Jesus really is.
There are lots of words for seeing in Greek, the word used to describe what the apostles are doing here has the sense of looking intensely, or studying, the way we might examine something that has us completely fascinated.
The apostles at this moment see clearly the divine nature of Christ, who is as we say in the creed "consubstantial with the Father." These three become, as Peter reminds us in the second reading, the eyewitnesses not just to the miracles but to the very identity of Jesus, true God and true man.
It would take centuries for the Church to fully grasp and articulate the meaning of what these three apostles saw that day. And I would dare say that, two millennia later, most of us still struggle to fully grasp the meaning, and how it impacts us. That God so loved us, that he became incarnate, truly united with us.
While we may never, in this life, see what they saw. Christ offers all people a share in that unity. Let us live today united with Christ, and let our true identity shine before the world.