Catechism of the Catholic Church §1117 — excerpt
As she has done for the canon of Sacred Scripture and for the doctrine of the faith, the Church, by the power of the Spirit who guides her "into all truth," has gradually recognized this treasure received from Christ and, as the faithful steward of God's mysteries, has determined its "dispensation."
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.