Today is the feast of the Transfiguration of the Lord.
The August 6 feast commemorates the revelation of Christ's divinity by him to Peter, James, and John on Mount Tabor (see Matthew 17:1-9).
The feast may have originally commemorated the dedication of the original basilica there. The Transfiguration has been observed in the East since the fifth century, but it did not enter the West until the middle of the ninth.
Pope Callistus III formally included it in the Roman Calendar in 1457 as a thank-offering for the victory of Christian troops over the Turks near Belgrade in 1456. In the Eastern Churches, it is still observed as one of the most important feasts of the year.
Here's a Year of Faith activity for the Transfiguration: In the Eastern churches, grapes are traditionally blessed on this day as a sign of the "First Fruits" of the harvest. If grapes aren't available, other summer fruits can be used. Visit a farmers' market and make a fruit salad with fresh grapes, apples, pears, peaches and melons.
(Information from Encyclopedia of Catholic Devotions and Practices by Ann Ball.)