Today, the 40th day after Christmas, is the Feast of the Presentation of the Lord. This Feast has a very solid biblical foundation:
When the days were completed for their purification according to the law of Moses, Mary and Joseph took Jesus up to Jerusalem to present him to the Lord, just as it is written in the law of the Lord, Every male that opens the womb shall be consecrated to the Lord, and to offer the sacrifice of a pair of turtledoves or two young pigeons, in accordance with the dictate in the law of the Lord.
On the 40th day after giving birth the Blessed Virgin Mary visited the temple to offer a sacrifice in accordance with the Law of Moses (Leviticus 12:1-8). She didn’t offer this sacrifice because she was actually made unclean by the birth of Christ but rather it was in order to fulfill “the prescriptions of the law of the Lord” (Luke 2:39). In imitation of this event in the 4th century the Church instituted the Feast of the Purification of the Blessed Virgin Mary to be celebrated on the 40th day after Christamas, February 2nd, every year.
This Feast had 3 emphases:
The Purification of the Blessed Virgin (Leviticus 12:7),
The Presentation of the child Jesus in the Temple (Luke 2:22),
and the recognition of Christ as the light to the Gentiles by the prophet Simeon (Luke 2:29-32)
In the revisions to the liturgy following the 2nd Vatican Council this feast was renamed the Feast of the Presentation of the Lord. The Purification of the Blessed Virgin and the recognition of Christ as the light to the Gentiles (represented by the blessing of candles which are then carried in procession before the Mass) seem to have been de-emphasized slighltly while the Presentation of Christ in the Temple has been emphasized. But, all of these aspects of the Feast are still quite evident in both the Ordinary and Extraordinary Forms of the Roman Rite.
In addition to the Mass we see these aspects of the Feast also displayed in the devotions of the Church. The Presentation of Jesus in the Temple is the 4th Joyful Mystery of the Rosary. Simeon’s proclamation of Christ as the light to the Gentiles (Luke 2:29-32), known as the Nunc Dimittis or the Canticle of Simeon, – is prayed every night in the Liturgy of the Hours in the Office of Compline (Night Prayer). And the idea of a ritual purification after childbirth can still be seen, albeit quite rarely, in a very beautiful ceremony known as the Churching of Women.