Catechism of the Catholic Church §1075 — excerpt
Liturgical catechesis aims to initiate people into the mystery of Christ (It is "mystagogy." ) by proceeding from the visible to the invisible, from the sign to the thing signified, from the "sacraments" to the "mysteries."
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.
Also cites: SC 3-4