Catechism of the Catholic Church §1575 — excerpt
Christ himself chose the apostles and gave them a share in his mission and authority. Raised to the Father's right hand, he has not forsaken his flock but he keeps it under his constant protection through the apostles, and guides it still through these same pastors who continue his work today.
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: Roman Missal, Preface of the Apostles I · LG 21