Some books seem to have been written, not to teach us anything, but to let us know that the author has known something.
— Goethe, Maxims and Reflections
Obscurity and vagueness of expression is always and everywhere a very bad sign: for in ninety-nine cases out of a hundred it derives from vagueness of thought, which in turn comes from an original incongruity and inconsistency in the thought itself, and thus from its falsity. If a true thought arises in a head it will immediately strive after clarity and will soon achieve it: what is clearly thought, however, easily finds the expression appropriate to it. The thoughts a man is capable of always express themselves in clear, comprehensible, and unambiguous words. Those who put together difficult, obscure, involved, ambiguous discourses do not really know what they want to say: they have no more than a vague consciousness of it which is only struggling towards a thought: often, however, they also want to conceal from themselves and others that they actually have nothing to say.
— Schopenhauer, Essays and Aphorisms
Those who know that they are profound strive for clarity. Those who would like to seem profound to the crowd strive for obscurity. For the crowd believes that if it cannot see to the bottom of something it must be profound. It is so timid and dislikes going into the water.
— Nietzsche, The Gay Science
[M]y ambition is to say in ten sentences what everyone else says in a book — what everyone else does not say in a book…
— Nietzsche, Twilight of the Idols
You would think that when a man had something worthwhile to say his chief concern would be to make himself understood and he would write as simply as he could. But it is not so. There are not above a score of scholars in this country at present who express themselves in lucid prose.
— Eric Hoffer, Before the Sabbath