Tertullian, Prescription against Heretics 36

If you want to put your curiosity to better use for your own salvation, then make the rounds of the apostolic churches. In those churches the very chairs of the apostles still preside in their original places, and their authentic letters are read aloud, echoing each apostle's voice and preserving his likeness. Is Achaia nearby? You have Corinth. Not far from Macedonia? You have Philippi and the Thessalonians. Able to reach Asia? You have Ephesus. If you border Italy, you have Rome, from which authority is also close at hand for us. What a blessed church! The apostles poured out their entire teaching there with their own blood; Peter matched the Lord's passion there; Paul was crowned with John's death there; and the apostle John, after being plunged into boiling oil and suffering no harm, was exiled to an island. Let us see what he learned and taught when he contended with the African churches as well. He acknowledges one God, the Creator of all, and Christ Jesus, the Son of God the Creator, born of the Virgin Mary, and the resurrection of the flesh. He blends the Law and the Prophets with the gospel and apostolic writings, draws his faith from them, seals it with water, clothes it with the Holy Spirit, feeds it with the Eucharist, urges it toward martyrdom, and on that basis admits no one who opposes this rule. This is the rule — not merely one that foretold future heresies, but the one from which heresies actually sprang. Yet they did not come from it, because they were formed against it. Even from the kernel of the olive a wild, bitter oleaster springs up; even from the poppy a most pleasing and sweet fig, a windy and empty caprifig, arises. So heresies come from our fruit, not our stock — from the grain of truth, but growing wild with falsehood.