At every step one has to wrestle for truth; one has to surrender for it almost everything to which the heart, to which our love, our trust in life, cling otherwise. That requires greatness of soul: the service of truth is the hardest service. What does it mean, after all, to have integrity in matters of the spirit? That one is severe against one's heart...that one makes of every Yes and No a matter of conscience.
Friedrich NietzscheHow much rationality and higher protection there is in such self-deception, and how much falseness I still require in order to allow myself again and again the luxury of my sincerity.
Friedrich NietzscheThat the world is not the embodiment of an eternal rationality can be conclusively proved by the fact that the piece of the worldthat we know--I mean our human reason--is not so very rational. And if it is not eternally and completely wise and rational, then the rest of the world will not be either; here the conclusion a minori ad majus, a parte ad totum applies, and does so with decisive force.
Friedrich Nietzsche