Not that I am ignorant that the opinions of philosophers have been various, of those I mean who have placed the chief good, that which I call the end, in the mind. And although some people have followed them very incorrectly, still I prefer their theory, not only to that of the three sects who have separated virtue from the chief good, while ranking either pleasure, or freedom from pain, or the original gifts of nature among goods, but also to the other three who have thought that virtue would be crippled without some reinforcement, and on that account have each added to it one of those other particulars which I have just enumerated. I,however, as I said, prefer to all these the men, whoever they may be, who have described the chief good as consisting in the mind and in virtue. But nevertheless, those also are extremely absurd who have said that to live with knowledge is the highest good, and who have asserted that there is no difference between things, and so, that a wise man will surely be a happy one, never at any moment of his life preferring one thing to another: as some of the Academics are said to have laid it down, that the highest good and the chief duty of a wise man is to resist appearances, and firmly to withhold his assent from them.
Now people often make very lengthy replies to each of these assertions; yet what is very clear ought not to be long. But what is more evident than, if there be no selection made, discarding those things which are contrary to nature, and selecting those which are according to nature, all that prudence which is so much sought after and extolled would be done away with? If, then, we discard those sentiments which I have mentioned, and all others which resemble them, it remains that the chief good must be to live, exercising a knowledge of those things which happen by nature, selecting what is according to nature, and rejecting any which are contrary to nature; that is to say, to live in a manner suitable and corresponding to nature.
But in other arts, when anything is said to have been done according to the rules of art, there is something to be considered which is subsequent and follows upon such compliance; which they call ἐπιγεννηματικόν. But when we say in any matter that a thing has been done wisely, that same thing is from the first said also to have been done most properly; for whatever proceeds from a wise man must at once be perfect in all its parts: for in him is placed that quality which we say is to be desired. For as it is a sin to betray one's country, to injure one's parents, to plunder temples, which are all sins of commission; so it is likewise a sin to be afraid, to grieve, to be under the dominion of lust, even if no overt act follows these feelings. But, as these are sins, not in their later periods and consequences, but at once from the first moment; so those actions which proceed from virtue are to be considered right at the first moment that they are undertaken, and not only when they are accomplished.