"I do not agree with what you say, but I will defend to the death your right to misattribute it to Voltaire."

-Voltaire

(The phrase was written by Evelyn Beatrice Hall as a summary of Voltaire's attitude toward free speech. Since then, people started attributing it to Voltaire himself, and the myth has spread far and wide, as nobody really checks to see if he actually said that. Hearing something somewhere is plenty of evidence for most people, most of the time, and the conviction gets more solid over time. Which brings me to my second rationality quote, from Winston Churchill: "A lie gets halfway around the world before the truth has a chance to get its pants on.")