This document discusses the Catholic understanding of prayer, liturgy, and sacraments. It begins with a prayer to the Holy Spirit and then provides definitions and explanations of key concepts. Liturgy is defined as the official public worship of the Church, especially the Eucharist. The sacraments are efficacious signs of grace that were instituted by Christ to give grace. The Church is considered the fundamental sacrament as it makes Christ present through the indwelling Spirit among its members.