We must therefore enter into the nature of things, and see thoroughly what it demands; for otherwise we cannot arrive at the knowledge of ourselves. And because this precept was too important an one to be discerned by a man, it has on that account been attributed to God. The Pythian Apollo, then, enjoins us to know ourselves: but this knowledge is to know the power of our mind and body, and to follow that course of life which enjoys the circumstances in which it is placed. And since that desire of the mind to have all the things which I have mentioned in the most perfect manner in which nature could provide them, existed from the beginning, we must admit, when we have obtained what we desired, that nature consists in that as its extreme point, and that that is the chief good: which certainly must in every case be sought for spontaneously for its own sake, since it has already been proved, that even all its separate partsare to be desired for their own sake. But if, in enumerating the advantages of the body, any one should think that we have passed over pleasure, that question may be postponed till another opportunity; for it makes no difference with regard to the present subject of our discussion, whether pleasure consists in those things which we have called the chief things in accordance with nature, or whether it does not. For if, as I indeed think, pleasure is not the crowning good of nature, it has been properly passed over: but if that crowning good does exist in pleasure, as some assert, then the fact does not at all hinder this idea of ours of the chief good from being the right one. For, if to those things which are the principal goods of nature, pleasure is added, then there will have been added just one advantage of the body; but no change will have been made in the original definition of the chief good which was laid down at first.