August 6, the feast of the Transfiguration, is observed by Catholics of both the Eastern and Roman rites on this day.

The account of the Transfiguration appears in each of the three Synoptic Gospels (Matthew 17:1–8, Mark 9–2–9, and Luke 9–28–36). All three chronologies of the event match remarkably well, placing it just after Peter's profession of faith in Jesus as the Messiah and Jesus' first prophecy of his suffering and death. Peter's enthusiasm to set up tents immediately implies that it happened during the autumn, during the week-long Jewish Feast of Booths.

Scripture scholars assert that despite the texts' agreement, reconstructing the disciples' experience is challenging since the Gospels primarily rely on Old Testament accounts of the Son of Man's prophetic visions and Sinai encounters with God. Certainly, Peter, James, and John saw a glimpse of Jesus' divinity that made them fearful. They used well-known theological terminology to describe an experience that defies expression. Undoubtedly, Jesus forewarned them that his splendor and his suffering would be intricately linked—a thought that John emphasizes often in his Gospel.

According to tradition, the revelation took place on Mount Tabor. August 6 marked the dedication of a church that had been built there in the fourth century. In the Eastern Church, a feast commemorating the Transfiguration was observed approximately at that time.

At Belgrade, on July 22, 1456, the Crusaders overcame the Turks. When news of the triumph reached Rome on August 6, Pope Callistus III instituted the feast the following year.