Catechism of the Catholic Church §748 — excerpt
"Christ is the light of humanity; and it is, accordingly, the heart-felt desire of this sacred Council, being gathered together in the Holy Spirit, that, by proclaiming his Gospel to every creature, it may bring to all men that light of Christ which shines out visibly from the Church."
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 1