The Church turns its gaze from our Lord's infancy and childhood to his public ministry, which will begin with His baptism (Matthew 3:13-17). The feast of our Lord's baptism is called the Theophany, meaning "the manifestation" or "appearance of God", and is celebrated on January 6.
During the days leading up to the Nativity, we sang the pre-festive hymn: "Bethlehem, make ready; Ephrathah, prepare youself." Beginning on January 2 at Vespers (that is, starting on the evening of January 1), we look to Galilee and the River Jordan and sing the pre-festive hymn of Theophany:
Zebulun, make ready; Naphtali, prepare yourself. O River Jordan, stand and leap for joy to receive the Master coming to be baptized. O Adam, rejoice with the first mother, Eve, and do not hide yourselves as once you did in Paradise. For, seeing you naked, Christ has appeared to put on the first robe. He has appeared to renew all creation.
Both events - the birth of Christ, and His baptism in the Jordan - were manifestations or appearances of God; in other words, theophanies. Each was a crucial step in God's plan of salvation for the human race.
By their holy intercessions, O Christ our God, have mercy on us and save us. Amen!