Catechism of the Catholic Church §858 — excerpt
Jesus is the Father's Emissary. From the beginning of his ministry, he "called to him those whom he desired; .... and he appointed twelve, whom also he named apostles, to be with him, and to be sent out to preach."
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.