A spring never free from the pressure of some foreign body at last loses its elasticity; and so does the mind if other people’s thoughts are constant… - Arthur Schopenhauer

It is a wise thing to be polite; consequently, it is a stupid thing to be rude. To make enemies by unnecessary and willful incivility, is just as insane a proceeding as to set your house on fire. For politeness is like a counter — an avowedly false coin, with which it is foolish to be stingy.

buying books would be a good thing if we also could buy the time to read them.

... that when you're buying books, you're optimistically thinking you're buying the time to read them.
(Paraphrase of Schopenhauer)