The Nativity Fast
The establishment of the Nativity Fast, as well as other multi-day fasts relates to the ancient times of Christianity. In the 4th century, the Holy Fathers St. Ambrose of Milan, Philistrius and Blessed Augustine mention the Nativity Fast in their writings. In the 5th century Leo the Great wrote about the Nativity Fast. At the Council of 1166 that was held in the time of Patriarch Luke of Constantinople and Byzantine emperor Manuel, a forty-day fast was established to be observed by all Christians before the great feast of the Nativity of Christ.
The Nativity Fast begins on November 15/28 for forty days until December 25/January 7. Since the Fast starts the day after the feast day of the Apostle Phillip (November 14/27), it's also called St. Phillip's Fast. The Nativity Fast helps us to mystically renew our spiritual unity with God in preparation for the Feast of the Nativity of Christ.
St. Leo the Great wrote: "Four periods [of the year] have been set aside as times of abstinence, so that over the course of the year we might recognize that we are constantly in need of purification, and that amid life’s distractions, we should always strive by means of fasting and acts of charity to remove sin: sin which is multiplied in our transitory flesh and in our impure desires."
According to Leo the Great, the Nativity Fast is a sacrifice to God in return for the gathered harvest. The Holy Hierarch stated, "Just as the Lord has generously granted us abundance of the fruits of the earth, so should we, during the time of this Fast, be generous to the poor."
According to St. Simeon of Thessalonica, "…the Forty-day Nativity Fast represents the fast undertaken by Moses, who, having fasted for forty days and forty nights, received the Commandments of God, written on stone tablets [of the Law]. And we, fasting for forty days, will reflect upon and receive from the Virgin of the living Word - not written upon stone, but born, incarnate, and we will commune of His Divine Body."
The Nativity Fast was established to help us through repentance, prayer and fasting to cleanse ourselves before the Nativity of Christ, so that with clean heart, soul, and body, we might reverently meet the Son of God, Who has come into the world and so that in addition to bringing the usual gifts and sacrifices, we might bring Him our clean hearts and a desire to follow His teachings.
May God grant that we all spend the salvific days of the Nativity Fast in such a way as to be a great benefit to our souls.