variation and error to such a degree, that they are supposed by some to exist conventionally only, and not in the nature of things: but then, again, the things which are allowed to be goods admit of a similar error, because harm comes to many from them: for before now some have perished through wealth, and others through valour.
We must be content then, in speaking of such things and from such data, to set forth the truth roughly and in outline; in other words, since we are speaking of general matter and from general data, to draw also conclusions merely general. And in the same spirit should each person receive what we say: for the man of education will seek exactness so far in each subject as the nature of the thing admits, it being plainly much the same absurdity to put up with a mathematician who tries to persuade instead of proving, and to demand strict demonstrative reasoning of a Rhetorician.
Now each man judges well what he knows, and of these things he is a good judge: on each particular matter then he is a good judge who has been instructed in it, and in a general way the man of general mental cultivation.2
Hence the young man is not a fit student of Moral Philosophy, for he has no experience in the actions of life, while all that is said presupposes and is concerned with these: and in the next place, since he is apt to follow the impulses of his passions, he will hear as though he heard not, and to no profit, the end in view being practice and not mere knowledge.
And I draw no distinction between young in years, and youthful in temper and disposition: the defect to which I allude being no direct result of the time, but of living at the beck and call of passion, and following each object as it rises.3 For to them that are such the knowledge comes to be unprofitable, as to those of imperfect self-control: but, to those who form their desires and act in accordance with reason, to have knowledge on these points must be very profitable.