Catechism of the Catholic Church §1136 — excerpt
Liturgy is an "action" of the whole Christ (Christus totus). Those who even now celebrate it without signs are already in the heavenly liturgy, where celebration is wholly communion and feast
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.