Catechism of the Catholic Church §1213 — excerpt
Holy Baptism is the basis of the whole Christian life, the gateway to life in the Spirit (vitae spiritualis ianua), and the door which gives access to the other sacraments.
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: Council of Florence: DS 1314: vitae spiritualis ianua · Roman Catechism II, 2, 5 · Council of Florence: DS 1314 · CIC, cann. 204 # 1 · 849 · CCEO, can. 675 # 1