Catechism of the Catholic Church §2204 — excerpt
"The Christian family constitutes a specific revelation and realization of ecclesial communion, and for this reason it can and should be called a domestic 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: FC 21 · LG 11