Catechism of the Catholic Church §1099 — excerpt
The Spirit and the Church cooperate to manifest Christ and his work of salvation in the liturgy. Primarily in the Eucharist, and by analogy in the other sacraments, the liturgy is the memorial of the mystery of salvation.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.