Quote by H. L. Mencken
Before a man speaks, it is always safe to assume that he is a fool. After he speaks it is seldom necessary to assume.
Summary
This quote suggests that it is generally prudent to view others with skepticism or caution until they prove their intelligence or wisdom through their words. It implies that people may reveal their lack of intellect or foolishness when they speak, and thus, the assumption of their foolishness is often confirmed after they share their thoughts or opinions. Essentially, the quote highlights the importance of critically evaluating a person's words and considering them less reliable until proven otherwise.