Catechism of the Catholic Church §7 — excerpt
"Catechesis is intimately bound up with the whole of the Church's life. Not only her geographical extension and numerical increase, but even more her inner growth and correspondence with God's plan depend essentially on catechesis."
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: CT 13