text: "Shall you then offer precepts that are clear, or precepts that are doubtful? Those which are clear need no counsellor, and doubtful precepts gain no credence; so the giving of precepts is superfluous. Indeed you should study the problem in this way: if you are counselling someone on a matter which is of doubtful clearness and doubtful meaning, you must supplement your precepts by proofs; and if you must resort to proofs, your means of proof are more effective and more satisfactory in themselves. 'It is thus that you must treat your friend, thus your fellow citizen, thus your associate.' And why? 'Because it is just.' Yet I can find all that material included under the head of Justice. I find there that fair play is desirable in itself, that we are not forced into it by fear nor hired to that end for pay, and that no man is just who is attracted by anything in this virtue other than the virtue itself. After convincing myself of this view and thoroughly absorbing it, what good can I obtain from such precepts, which only teach one who is already trained? To one who knows, it is superfluous to give precepts; to one who does not know, it is insufficient. For he must be told, not only what he is being instructed to do, but also why. I repeat, are such precepts useful to him who has correct ideas about good and evil, or to one who has them not? The latter will receive no benefit from you; for some idea that clashes with your counsel has already monopolized his attention. He who has made a careful decision as to what should be sought and what should be avoided knows what he ought to do, without a single word from you. Therefore, that whole department of philosophy may be abolished.