Clement of Rome (attributed)

Let us, therefore, fear the judgment which awaits teachers. For a severe judgment will those teachers receive "who teach, but do not," and those who take upon them the name of Christ falsely, and say: We teach the truth, and yet go wandering about idly, and exalt themselves, and make their boast "in the mind of the flesh." These, moreover, are like "the blind man who leads the blind man, and they both fall into the ditch." [Matthew 15:14] And they will receive judgment, because in their talkativeness and their frivolous teaching they teach natural wisdom and the "frivolous error of the plausible words of the wisdom of men," "according to the will of the prince of the dominion of the air, and of the spirit which works in those men who will not obey, according to the training of this world, and not according to the doctrine of Christ." But if thou hast received "the word of knowledge, or the word of instruction, or of prophecy," [1 Corinthians 12:8-10] blessed be God, "who helps every man without grudging — that God who gives to every man and does not upbraid him." [James 1:5]