The Byzantine Liturgy for this feast says that Christ revealed his glory to his disciples so they would know that his sufferings were completely voluntary, completely gift. It was God coming down, bringing himself to our level. God looked at us in love and came to us, so that we might approach God. When we do not look at others in love, do not come down the mountain of our own glorification to reach out to them, we are in danger of sin. Sin hurts us as well as others.
Sin is a rift tearing at every fabric of our lives.
He came, as we heard last Sunday, to announce the good news. He came down to share our suffering and death, so he could conquer both. Love conquers all separation and reconciles us to each and God.