I am again reminded here of Seneca’s saying: “_Si vis tibi omnia subjicere, te subjice rationi_.” Since, however, as was shown in the fourth book, the nature of suffering is positive, and that of pleasure negative, he who takes abstract or rational knowledge as the rule of his conduct, and therefore constantly reflects on its consequences and on the future, will very frequently have to practise _sustine et abstine_, for in order to obtain the life that is most free from pain he generally sacrifices its keenest joys and pleasures, mindful of Aristotle’s “ὁ φρονιμος το αλυπον διωκει, ου το ἡδυ” (_quod dolore vacat, non quod __ suave est, persequitur vir prudens_). Therefore with him the future constantly borrows from the present, instead of the present borrowing from the future, as is the case with a frivolous fool, who thus becomes impoverished and finally bankrupt. In the case of the former reason must, for the most part, assume the _rôle_ of a churlish mentor, and unceasingly call for renunciations, without being able to promise anything in return, except a fairly painless existence. This rests on the fact that reason, by means of its conceptions, surveys the _whole_ of life, whose outcome, in the happiest conceivable case, can be no other than what we have said. When this striving after a painless existence, so far as it might be attainable by the application of and strict adherence to rational reflection and acquired knowledge of the true nature of life, was carried out with the greatest consistency and to the utmost extreme, it produced cynicism, from which stoicism afterwards proceeded. I wish briefly here to bring this out more fully for the sake of establishing more firmly the concluding exposition of our first book.