No rose without a thorn but many a thorn without a rose.

There are, first of all, two kinds of authors: those who write for the subject's sake, and those who write for writing's sake. ... The truth is that when an author begins to write for the sake of covering paper, he is cheating the reader; because he writes under the pretext that he has something to say.

Life is short and truth works far and lives long: let us speak the truth.

This world could not have been the work of an all-loving being, but that of a devil, who had brought creatures into existence in order to delight in the sight of their sufferings.

A man must have grown old and lived long in order to see how short life is.

No one writes anything worth writing, unless he writes entirely for the sake of his subject.

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.