Philosophy ... is a science, and as such has no articles of faith; accordingly, in it nothing can be assumed as existing except what is either positively given empirically, or demonstrated through indubitable conclusions.
It is only the man whose intellect is clouded by his sexual impulse that could give the name of the fair sex to that undersized, narrow-shouldered, broad-hipped, and short-legged race.
(Politeness is) a tacit agreement that people's miserable defects, whether moral or intellectual, shall on either side be ignored and not be made the subject of reproach.
What disturbs and depresses young people is the hunt for happiness on the firm assumption that it must be met with in life. From this arises constantly deluded hope and so also dissatisfaction. Deceptive images of a vague happiness hover before us in our dreams, and we search in vain for their original. Much would have been gained if, through timely advice and instruction, young people could have had eradicated from their minds the erroneous notion that the world has a great deal to offer them.
There is no absurdity so palpable but that it may be firmly planted in the human head if you only begin to inculcate it before the age of five, by constantly repeating it with an air of great solemnity.
Many books serve merely to show how many ways there are of being wrong, and how far astray you yourself would go if you followed their guidance. You should read only when your own thoughts dry up.
I observed once to Goethe that when a friend is with us we do not think the same of him as when he is away. He replied, "Yes! because the absent friend is yourself, and he exists only in your head; whereas the friend who is present has an individuality of his own, and moves according to laws of his own, which cannot always be in accordance with those which you form for yourself.