Catechism of the Catholic Church §807 — excerpt
The Church is this Body of which Christ is the head: she lives from him, in him, and for him; he lives with her and in her.
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.