“It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt.”
The earliest known appearance of this saying is Maurice Switzer's 1907 book Mrs. Goose, Her Book. No version appears anywhere in Twain's writings, and the attribution to him arrived later and stuck because it sounds like him.
- — Garson O'Toole, Quote Origin: Better to Remain Silent and Be Thought a Fool than to Speak and Remove All Doubt (Quote Investigator) (2010)

