It’s easier to fool people than it is to convince them they have been fooled.

This quote has been attributed to Mark Twain. The irony is that there are no references showing Mark Twain saying these words. And yet the uninformed continue to credit him with this proverb.

How do you know whether the truth you believe to be true is actually the truth? Most people work hard to defend what they think is true and never question whether new ideas might be valid. There is security in "knowing" you are right.