In the first reading, God makes a covenant with Abram and promises him descendants and land.
The psalm reminds us once again that all we really need is God, he is our light and salvation and will care for us when we call out to him. The second reading from Philippians asks us to remember that our goal is heaven and we should stand firm knowing the Jesus will "change our lowly body to conform with his glorified body by the power that enables him also to bring all things into subjection to himself." Finally, the Gospel is the Transfiguration of Christ.
Often with this scripture comes the analogy of a person going on retreat or a mission trip and not wanting to leave to return to the real world. We all long for mountaintop experiences, but we live in the world where that 'high' is difficult if not impossible to maintain. But the other day when reading this, I was hit with Peter's denial of Jesus a sort time after this happens. Peter, along with James and John, hears God saying this is my son but does he understand? This lack of understanding or maybe his inability to live out this knowledge, really helps me. Peter went on to be the first Pope, Jesus said he was the rock, and he still did not always live out his faith. He made mistakes. And so, if Jesus choose Peter, with all his flaws then Jesus can and does choose each one of us, as imperfect as we are, to help build his kingdom here on earth.
Practically speaking, how do we do this? We do it in our homes and work place, with our families, friends, and coworkers; always striving to be kind, considerate, helpful, in short, following the greatest commandment, "Love your neighbor as yourself." It is that simple. It is that difficult.