Irenaeus of Lyons, Against Heresies 5.20

All these heretics came long after the bishops to whom the Apostles entrusted the churches, a point we proved in the third book with every care. Because they are blind to the truth, they are forced to wander off onto one divergent path after another, so the footprints of their teaching lie scattered in discordant, incoherent disarray.

But those who belong to the Church walk the whole world over, bearing a firm tradition from the Apostles that lets us see one and the same faith everywhere: one and the same God the Father worshipped by all, the same mystery of the Son's incarnation believed, the same gift of the Spirit received, the same precepts pondered, the same pattern of ordination that serves the Church preserved, the same hope of the Lord's return cherished, and the same salvation of the whole person—soul and body—upheld.

The Church's preaching is true and steadfast, and in it the single way of salvation is displayed throughout the world. To the Church has been entrusted the light of God; therefore the wisdom of God, by which He saves all people, is sung in the streets, acts with authority in the squares, is proclaimed from the highest walls, and speaks constantly at the gates. Everywhere the Church preaches the truth, and she is the lamp that carries the light of Christ.

Those who abandon the Church's preaching accuse the saints of ignorance, never weighing how far the godly person surpasses the blasphemous, shameless sophist. All heretics are of this stripe, along with those who imagine they have discovered something beyond the truth. Following the paths already laid out, they make their journey in varied, shapeless, feeble ways, never holding the same convictions twice, like blind men led by the blind. Justly they fall into the pit of hidden ignorance, always searching, never finding the truth.

We must therefore flee their opinions and keep a more intent watch, so that we are not shaken by them; we must take refuge in the Church, be reared in her bosom, and be nourished with the Lord's own food. For the Church has been planted as a paradise in this world. 'From every tree of the garden you may eat,' says the Spirit of God—that is, from every Scripture that belongs to the Lord you may eat; but from the tree of the knowledge of good and evil you must not eat, nor touch the whole heretious dissent (Genesis 2:17).

The heretics themselves claim to possess the knowledge of good and evil, and they hurl their impious judgments against the God who made them, presuming to know more than the measure of perception allows. That is why the Apostle warns: 'Do not be wise beyond what it is fitting to be wise, but be wise unto sobriety' (Romans 12:3), lest by eating their knowledge—which is wiser than it ought to be—we be cast out of the paradise of life. Into that paradise the Lord leads those who obey Him, recapitulating in Himself all things in heaven and on earth. The things in heaven are spiritual; the things on earth are ordered according to man's nature.

He has recapitulated everything in Himself, joining man to the Spirit and placing the Spirit in man. He Himself became the head of the Spirit, and gives the Spirit to be the head of man, for through Him we see, and hear, and speak.