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.
Arthur Schopenhauer (2012). “Collected Essays of Arthur Schopenhauer”, p.58, Simon and Schuster