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." Such catechesis is to be presented by local and regional catechisms. This Catechism, which aims to serve the whole Church in all the diversity of her rites and cultures, 15 will present what is fundamental and common to the whole Church in the liturgy as mystery and as celebration, and then the seven sacraments and the sacramentals.