Catechism of the Catholic Church §1549 — excerpt
Through the ordained ministry, especially that of bishops and priests, the presence of Christ as head of the Church is made visible in the midst of the community of believers.
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 21 · St. Ignatius of Antioch, Ad Trall. 3, 1: SCh 10, 96 · Ad Magn. 6, 1: SCh 10, 82-84