Chapter 11 — Part I: The Creed — Article IX: The Holy Catholic Church; the Communion of Saints
Section 30. It is the unanimous teaching of the Fathers that this visible head is necessary to establish and preserve unity in the Church. This St. Jerome clearly perceived and as clearly expressed when, in his work against Jovinian, he wrote: One is elected that, by the appointment of a head, all occasion of schism may be removed. In his letter to Pope Damasus the same holy Doctor writes: Away with envy, let the ambition of Roman grandeur cease! I speak to the successor of the fisherman, and to the disciple of the cross. Following no chief but Christ, I am united in communion with your Holiness, that is, with the chair of Peter. I know that on that rock is built the Church. Whoever will eat the lamb outside this house is profane; whoever is not in the ark of Noah shall perish in the .flood.