(St.) Bernard sees that the Sacrament (of Advent) is the Presence of Christ in the world as Savior. In his theology Advent does not merely commemorate the Incarnation as a historical event, nor is it a mere devotional preparation for the Feast of Christmas, nor an anticipation of the Last Judgment. It is above all the “sacrament” of the Presence of God in the world and in time in His Incarnate Word, in His Kingdom, above all His presence in our own lives as our Savior. The sacrament of Advent is the necessaria praesentia Christi. Here he repeats in more concrete and practical terms his statement of the necessity of our finding Christ the Savior here and now among us . . . .
Thomas Merton
Seasons of Celebration, p. 64