[265] And if neither the learner nor the teacher exists, the method of teaching also is abolished.

[266] And it is no less disputed on the following grounds. The method of teaching comes to exist either by ocular evidence or by speech; ¹ but it does not come to exist either by ocular evidence or by speech, as we shall show; therefore the method of learning also is not easy to discover.

Now teaching does not come by ocular evidence, since ocular evidence consists in things exhibited. But what is exhibited is apparent to all; and the apparent, qua apparent, is perceptible by all; and what is perceptible by all in common is incapable of being taught; therefore nothing is capable of being taught by ocular evidence.

[267] Nor, in fact, is anything taught by speech. For speech either signifies something or signifies nothing. But if it signifies nothing, neither will it be capable of teaching anything. And if it signifies something, it does so either by nature or by convention. But it is not significant by nature ² because all men do not understand all when they hear them, as is the case with Greeks hearing barbarians talk or barbarians hearing Greeks.

[268] And if it is significant by convention, evidently those who have grasped beforehand the objects to which the several words are assigned will perceive those objects, not through being taught by the words things of which they were ignorant, but by recollecting and recovering things which they knew; whereas those who require to learn what they do not know, and who are ignorant of the objects to which the words are assigned, will have no perception of anything.

[269] Consequently, the method of learning also will be incapable of subsisting. For, in fact, the teacher ought to impart to the learner an apprehension of the principles of the art he is teaching, so that the latter by apprehending them as a system may thus become an expert artist. But, as we have shown above, ³ apprehension is nothing; therefore also the method of teaching cannot subsist. But if neither the matter taught exists, nor the teacher and the learner, nor the method of learning, then neither learning exists nor teaching.

[270] Such, then, are the objections put forward regarding learning and teaching in general. And the same difficulties may also be alleged in the case of the so-called art of living. Thus, for instance, we have shown above ⁴ that the matter taught, namely prudence, is non-existent; and both the teacher and the learner are non-existent. For either the prudent man will teach the prudent the art of living, or the imprudent the imprudent, or the imprudent the prudent, or the prudent the imprudent; but none of these teaches any other; therefore the so-called art of living is not taught.

[271] Probably it is superfluous even to refer to the other cases; but if the prudent man teaches prudence to the imprudent, and prudence is ‟knowledge ⁵ of things good and evil and neither,” the imprudent man, as he does not possess prudence, possesses ignorance of the things that are good and evil and neither; and since he possesses nothing but ignorance thereof, when the prudent man teaches him what things are good and evil and neither, he will merely hear what is said and will not get to know the things. For if he should grasp them while in a state of imprudence, then imprudence too will be capable of perceiving what things are good and evil and neither.

[272] But, according to them, imprudence is certainly not capable of perceiving these things, since, if it were, the imprudent man will be prudent. Therefore, according to the definition of prudence, the imprudent man does not grasp what is said or done by the prudent. And, as he fails to grasp, he will not be taught by him, especially since, as we have said above, he cannot be taught either by ocular evidence or by means of speech. But, in fine, if the so-called art of living is not imparted to anyone either by means of learning and teaching or by nature, then the art of living, so harped on by the philosophers, is indiscoverable.

[273] Yet even were one to grant, as an act of bounty, that this visionary art of living is imparted to someone, it will show itself to be hurtful to its possessors, and a cause of perturbation, rather than beneficial.