Ad Petri Cathedram §65

⁶⁵ When the Divine Redeemer founded His Church, there is no doubt that He made firm unity its cornerstone and one of its essential attributes. Had He not done this—and it is absurd even to make such a suggestion—He would have founded a transient thing, which in time, at least, would destroy itself. For in just this way have nearly all philosophies risen from among the vagaries of human opinion: one after another, they come into being, they evolve, they are forgotten. But this clearly cannot be the history of a divine teaching authority founded by Jesus Christ, "the way, the truth, and the life."(22)