On Transfiguration Sunday, we hear the voice of the Father speak out of a cloud: "This is my Son, the Beloved; listen to him!" This, as the Light of Jesus' divinity shines before Peter, James, John, and us, blinding. This is the very same light which we celebrated on Christmas Eve, as the Light of our God incarnate shone on a people in deep darkness. The Father's voice which we heard in Jesus' baptism, in Jesus' transfiguration bookends this theme of the light of the revelation of the Son of God. Transfiguration is the culmination and (temporary) end of this season of Light.
The light is not precisely gone. There is a light brighter even than the light of Jesus' transfiguration, a light which is the Church's sole reason for existing: the Light of Jesus' resurrection. But between the light of the Transfiguration and the light of the Resurrection there is a dark valley to be travelled.
This chasm we call Lent. Lent is a season of repentance, and spiritual preparation for the feast of our Lord's resurrection. It seems the light of Christ's incarnation reveals much, too much, of us: it reveals the sins we would rather keep hidden, and it reveals the paths by which we avoid looking too closely at ourselves and our choices. Standing before the radiance of the Son of God, the ways in which we have become creatures of darkness are all the more clear.
And so we need Lent. We need the desert. We need the ashes on Ash Wednesday. We need the desolate places of the spiritual life, in order to journey from the grace of our creation, unto the double-grace of God's holy redemption.
So let us reach up, and let Jesus take us by the hand, and go where we do not wish to go. The desert beckons. The Spirit drives us out. And we will find, as we approach the terrible mystery of Good Friday, that even wandering in the desert, we are not without divine fire and cloud—just enough light—to guide us.