The Nativity Cycle
As Orthodox Christians, we begin the celebration of the Nativity of Christ — on January 6— with a time of preparation. Forty days before the feast of the birth of Our Lord we enter the period of the Christmas Fast: to purify both soul and body to enter properly into and partake of the great spiritual reality of Christ’s Coming. This fasting season does not constitute the intense liturgical season that is characteristic of Great Lent; rather, Christmas Lent is more of an "ascetical" rather than "liturgical" nature. Nevertheless, the Christmas fasting season is reflected in the life of the Church in a number of liturgical notes that announce the coming feast.
Within the forty days preparation the theme of the approaching Nativity is introduced in the services and liturgical commemorations, little by little. On the eve of the Feast of the Entrance of the Theotokos into the Temple, we hear the first announcement from the nine hirmoi of the Christmas Canon: "Christ is born, glorify Him!"