Catechism of the Catholic Church §904 — excerpt
"Christ . . fulfills this prophetic office, not only by the hierarchy . . but also by the laity. He accordingly both establishes them as witnesses and provides them with the sense of the faith [sensus fidei] and the grace of the word"
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: LG 35 · St. Thomas Aquinas, STh. III, 71, 4 ad 3