Luke 2:24

and to offer a sacrifice according to that which is said in the Law of the Lord, a pair of turtledoves or two young pigeons.

Luke finds it necessary to explain the rites connected with the purification for the sake of his readers that were not familiar with Jewish laws. The mother was unclean, according to the ordinances of Moses, for seven days after the birth of a son, and must then remain separate for a matter of another thirty-three days. These forty days altogether denoted the days of the Levitical cleansing, or purification, Leviticus 12:1. At the close of this period the parents went up to Jerusalem with the Child to present Him to the Lord, for the firstborn of man and beast belonged to the Lord, Exodus 13:2, and had to be redeemed with a sacrifice. Since Mary and Joseph were poor, they could not afford to bring a lamb. Mary therefore brought the less expensive sacrifice, Leviticus 12:6. The manner in which Mary brought her sacrifice, the sin-offering and the offering of thanksgiving, is the following. She entered the Temple through the "gate of the firstborn," waited at the gate of Nicanor while the offering of incense was being made in the Holy Place. She then proceeded to the highest step of the stairway which led from the Court of the Women to the Court of Israel. Here a priest took the sacrifice from her hand and made the offering. She was then sprinkled with the blood to indicate the cleansing. Finally she paid five pieces of silver into the Temple treasury, placing the money (about 85 cents) into one of the trumpet-shaped treasure-boxes which stood in the Court of the Women. Note: The law really concerned only such women as became mothers after the visual course of nature. The Virgin and her Child might fitly have claimed exemption. But Christ humbled Himself so completely for the sake of us sinners, so completely did He want to become flesh of our flesh, that He submitted even to this humiliating rite of purification in the Temple.