“The liturgy is not exclusively a form of instruction, even though it is wholly instructive and includes some formal periods of instruction. It is an active memorial, a presence and a realization, in short, a celebration of the Christian mystery itself—of the whole Christian mystery, for if the liturgy celebrates particular mysteries successively, according to its well-known sequences of feasts—Christmas, Epiphany, Presentation in the Temple, our Lord’s fast, the Passion and Resurrection, etc.—they all form a unique cycle. It is like a unique celebration reaching its climax or innermost center by means of preparation and successive stages. Christmas, Epiphany and our Lord’s fast find their whole meaning in Easter, the mystery of death inseparable from the mystery of new life. Whatever the feast, it is always the celebration of the Covenant, whose sacrament is the Mass, the heart of all the feasts, which is also the memorial of the Lord’s Pasch.
The liturgy adds a sanctoral cycle to its temporal one, because it never separates the Body from the Head, the saints from their Lord and Master. In the celebration of the liturgy the whole mystical vine of salvation is communicated. It is truly the total reality of the Covenant that is offered to us.
It is not only taught to us or merely brought to our notice; it is celebrated, realized, rendered present and communicated not simply as a doctrine and truth, but as a reality. The doctrinal feasts were instituted relatively recently. They have a lot to recommend them, but even before the institution of a feast of Christ the King the liturgy was from beginning to end, and still is, the very realization and proclamation of the universal Lordship of Christ; it taught and teaches this by all that it is; it brings home this truth in a living way, exactly as a family inculcates the sense of duty in a child without giving him theoretical lessons on the subject. There was talk of instituting a feast of Redemption! It is unlikely that this will happen, and it would be quite superfluous if proper use is made of the liturgy, because the liturgy is, from beginning to end, the active celebration of the Redemption, and its efficacious enactment. The liturgy does not theorize on the Redemption, but it ceaselessly brings us into loving communication with Christ our Savior, with his Cross and its fruit, the hope of eternal life. Similarly…the liturgy teaches scarcely any lesson about the Eucharist—and none before the institution of the feast of Corpus Christi in 1264. But the liturgy celebrates the Eucharist; it offers us the means by which we may prepare ourselves to approach it; the liturgy brings us into communication with it and envelops it in a whole cult and worship, which radiates naturally from it.”
-Yves Congar in The Meaning of Tradition.