(from Prescription Against Heretics, c. 197 A.D.)
Grant, then, that all have erred; that the apostle was mistaken in giving his testimony; that the Holy Ghost had no such respect to any one (church) as to lead it into truth, although sent with this view by Christ, and for this asked of the Father that He might be the teacher of truth; grant, also, that He, the Steward of God, the Vicar of Christ , neglected His office, permitting the churches for a time to understand differently, (and) to believe differently, what He Himself was preaching by the apostles,–is it likely that so many churches, and they so great, should have gone astray into one and the same faith? No casualty distributed among many men issues in one and the same result. Error of doctrine in the churches must necessarily have produced various issues. When, however, that which is deposited among many is found to be one and the same, it is not the result of error, but of tradition. Can any one, then, be reckless enough to say that they were in error who handed on the tradition?
In whatever manner error came, it reigned of course only as long as there was an absence of heresies? Truth had to wait for certain Marcionites and Valentinians to set it free? During the interval the gospel was wrongly preached; men wrongly believed; so many thousands were wrongly baptized; so many works of faith were wrongly wrought; so many miraculous gifts, so many spiritual endowments, were wrongly set in operation; so many priestly functions, so many ministries, were wrongly executed; and, to sum up the whole, so many martyrs wrongly received their crowns! Else, if not wrongly done, and to no purpose, how comes it to pass that the things of God were on their course before it was known to what God they belonged? that there were Christians before Christ was found? that there were heresies before true doctrine? Not so; for in all cases truth precedes its copy, the likeness succeeds the reality. Absurd enough, however, is it, that heresy should be deemed to have preceded its own prior doctrine, even on this account, because it is that (doctrine) itself which foretold that there should be heresies against which men would have to guard! To a church which possessed this doctrine, it was written–yea, the doctrine itself writes to its own church–“Though an angel from heaven preach any other gospel than that which we have preached, let him be accursed.”
 “Vicar of Christ” means the Holy Spirit–B.A.S.