The feast of Transfiguration is first attested in the Christian East in the 5th century and it only appears in the Roman-Frankish area in the 10th century. The origin of the feast probably goes back to the dedication of a church on Mount Tabor, that is regarded as the Mount of Transfiguration.
The liturgy of the three cycles offers accounts about transfiguration from the synoptic gospels. These narratives show clear parallels to the accounts about the baptism of Jesus: both of them are events of theophanies – revelations of God (This is my beloved Son, with whom I am well pleased). Highlighting this connection between baptism and transfiguration, the Evangelic church celebrates Transfiguration always on the 6th (last) Sunday after Epiphanias.
The reading from 2 Peter 1:16-19 also makes reference to this event.
There used to be a custom in Rome to bless fresh grapes and other early fruits on August 6. This custom is still preserved in the Russian Orthodox Church, although there is no apparent connection with the transfiguration of Jesus.