On the Tilling of the Earth by Noah (161-165)

And those who do not arrive at this point are by philosophers indeed called wise men, but it is without their own knowledge: for they say that it is impossible for them who have advanced as far as the perfection of wisdom, and who have now for the first time reached its summit to be aware of their own perfection; for they affirm that it is impossible for both these things to happen at the same time, namely the arrival at the desired goal, and the apprehension that one has arrived there; but they affirm that on the border between the two, there is ignorance, of such a sort, that it is not far removed from knowledge, but that it is very near to it, and close to its doors.

When a man has acquired this, and thoroughly comprehends it, and is entirely acquainted with the powers of his adversaries, it will be his task to war against

But the man who is elevated by self-sufficiency, not being acquainted with the skill or power of his adversaries, will undoubtedly meet with disaster before he can do anything, and will endure the death of knowledge, which is a more grievous death than that which separates the soul from the body.

And this ought to happen to those who allow themselves to be deceived by the sophists; for when they are not able to find a solution for their sophisms, believing their fallacies as if they were true statements, they die as to the life of knowledge, suffering the same thing that they do who are cajoled by flatterers; for in the case of those men too, their soul, while in a healthy and genuine state, is driven off and overthrown by a friendship which is diseased in its very nature.

We must therefore advise those who are beginning to learn not to go forth into such contests, for they have not sufficient knowledge; and we must counsel those who are making some progress to abstain from them, because they are not perfect; and those who have now for the first time just attained to perfection, we must urge to forbear, because in some degree their perfection has escaped their own notice.