In order to understand the full meaning of the liturgy we have to grasp the liturgical conception of time.
The Christian “present” of the liturgy has some thing of the character of eternity, in which all reality is present at once. The past and the future are there fore made present in the mysteries of the liturgy. In the Advent mystery, the Church not only re-lives the longing of the prophets and the patriarchs for the Redeemer, not only prays to God for the grace of a “new nativity” at Christmas, but also anticipates the coming of Christ at the Last Day. In every liturgical mystery the Church embraces the whole history of man’s salvation, while concentrating her attention, for the time being, on one particular moment of that history.
At Christmas, we celebrate the coming of God into the world. We look especially at His birth at Bethlehem and see how that birth reveals to us the infinite mercy of God. But at the same moment we return to the very beginning of all. The generation of the Word in the bosom of the Father is also present to us, and we go forward to the end of all when, having come again into the world at the Last Judgment, and taken all things to Himself, and made all things new, we ourselves will share, by glory, in His divine and eternal sonship and hear the voice of the Father saying to us, in Him: “This day have I begotten thee!”
Thomas Merton
Seasons of Celebration, p. 56
