When you are trying to impress people with words, the more you say, the more common you appear, and the less in control. Even if you are saying something banal, it will seem original it you make it vague, open-ended, and sphinxlike. Powerful people impress and intimidate by saying less. The more you say, the more likely you are to say something foolish. –Robert Greene, The 48 Laws of Power (review)
Even a fool, when he keeps silent, is considered wise;
When he closes his lips, he is considered prudent.