Chapter 11 — Part I: The Creed — Article IX: The Holy Catholic Church; the Communion of Saints
Section 31. The same doctrine was long before established by Saints Irenaeus and Cyprian. The latter, speaking of the unity of the Church observes: The Lord said to Peter, I say to thee, Peter! thou art Peter: and upon this rock I will build my Church. He builds His Church on one. And although after His Resurrection He gave equal power to all His Apostles, saying: As the Father hath sent me, I also send you, receive ye the Holy Ghost; yet to make unity more manifest, He decided by His own authority that it should be derived from one alone, etc.