The feast of the Transfiguration probably had its origin in the annual commemoration of the dedication of a basilica built on Mount Tabor to honor this miraculous event in the life of Jesus. According to an ancient tradition, the episode of the Transfiguration took place 40 days before the crucifixion of Jesus; thus, the date of the feast was set 40 days before that of the Exaltation of the Holy Cross (September 14). It began to be celebrated in the West from the 9th century, and was included in the Roman calendar by Pope Callistus III in 1457, in thanksgiving for the victory of the Christian troops against the Turks, who were seriously threatening the West, in the battle of Belgrade the previous year. At the center of the feast is, of course, the mystery of the Transfiguration, which is linked to the vision of the Ancient One seated on the throne of fire and the appearance of the Son of Man (cf. First Reading).
