For after he had told the disciples of his coming death, on the holy mountain he manifested to them his glory, to show, even by the testimony of the law and the prophets, that the Passion leads to the glory of the Resurrection.
The Church on the second Sunday of Lent, puts before us the transfiguration, because we need to be reminded that our destination is the Glory of the Resurrection and we are passing through the long road of Lent; also passing through the long road of this life, but our citizenship is in Heaven. We need to be reminded of the Resurrection Glory to be strengthened in faith to deal with the sufferings of this life