On February 2 in the Orthodox Church, we commemorate the Presentation of our Lord and Savior Jesus Christ into the Temple, also known as The Meeting of our Lord, and the Feast of Lights. This takes place on the 40th day following Nativity.
According to ancient Jewish religious practices, as set down by the Mosaic Law (Leviticus 12, Exodus 13:12-15), a period of 40 days from the birth of an infant must pass before the mother and child could enter the Temple in Jerusalem. This 40 day period allowed the mother of a newly born infant to recover from her pregnancy, become well acquainted with her child, settle into her new role and routine, and subsequently be excused from her religious duties. Furthermore it was the time allocated by the Mosaic Law (Lev. 12:2-4) in which a mother and child would undergo the process of “purification” (spiritual preparation), so that the two could present themselves within the Temple, with the mother reassuming her religious obligations, while the infant being initiated into Jewish religious life. – Mode of Life
This feast has been celebrated by Christians since at least the 4th century, as attested to by a homily written for the occasion by Bishop Methodius of Patara who died in 312. It is also mentioned in the Pilgrimage of Egeria:
But certainly the Feast of the Purification is celebrated here with the greatest honour. On this day there is a procession to the Anastasis; all go in procession, and all things are done in order with great joy, just as at Easter. All the priests preach, and also the bishop, always treating of that passage of the Gospel where, on the fortieth day, Joseph and Mary brought the Lord into the Temple, and Simeon and Anna the prophetess, the daughter of Famuhel, saw Him, and of the words which they said when they saw the Lord, and of the offerings which the parents presented. And when all things have been celebrated in order as is customary, the sacrament is administered, and so the people are dismissed.
In the Orthodox Church, it is still customary for a mother and child to be churched on the 40th day.
Hate taking down your Christmas decorations? While many Christians put away Christmas decorations on the 12th Day of Christmas (which is the 12th day after Christmas), it is also customary to wait until this 40th day. Thus, it would also be appropriate to listen to Christmas music up to this point.