The story of the Transfiguration appears in all three Synoptic Gospels (St Mark, St Matthew, St Luke) The Gospel story is read twice during the Liturgical year on the 2nd Sunday of Lent and on today’s Feast day. The revelation of the Transfiguration occurs shortly after St Peter’s profession of faith, that Jesus is the Messiah, the Holy one of God.
Jesus had already prophesied that he was to suffer and die. In his Transfiguration, Jesus temporarily lifts the veil, as he had not yet died and entered into his glory. He gives Peter, James and John a glimpse of his divinity, demonstrating that his passion and death are not an end in themselves but will lead to his glorification. The Transfiguration reminds us that we cannot by pass the cross, whatever form that takes shape in our own lives and enter into glory. Our crosses accepted willingly, will also lead to our own glorification and resurrection.
Tradition suggests that this Revelation took place on Mount Tabor and a church was erected here in the 4th century. Around this time a feast was celebrated in the East and in the West, it was also celebrated in some places from the 8th century. On the 22ndof July 1456 the crusaders defeated at Belgrade the Turks and this news reached Rome on the 6th of August that same year. Pope Callistus III then the following year placed the Feast in the Roman calendar.
From the Summa Theologica of St Thomas Aquinas
“At his Transfiguration Christ showed his disciples the splendour of his beauty to which he will shape and colour those who are his. He will transform our lowliness configured to the body of his glory”