John

“One of the major difficulties Trillian experienced in her relationship with Zaphod was learning to distinguish between him pretending to be stupid just to get people off their guard, pretending to be stupid because he couldn't be bothered to think and wanted someone else to do it for him, pretending to be outrageously stupid to hide the fact that he actually didn’t understand what was going on, and really being genuinely stupid. He was renowned for being amazingly clever and quite clearly was so—but not all the time, which obviously worried him, hence, the act. He preferred people to be puzzled rather than contemptuous.”
― Douglas Adams, The Hitchhiker's Guide to the Galaxy

“Honestly, if you were any slower, you’d be going backward.”
― J.K. Rowling, Harry Potter and the Chamber of Secrets

“To be stupid, and selfish, and to have good health are the three requirements for happiness - though if stupidity is lacking, the others are useless.”
― Julian Barnes, Flaubert's Parrot

“Stupidity—The top of the list for Satanic Sins. The Cardinal Sin of Satanism. It’s too bad that stupidity isn’t painful. Ignorance is one thing, but our society thrives increasingly on stupidity. It depends on people going along with whatever they are told. The media promotes a cultivated stupidity as a posture that is not only acceptable but laudable. Satanists must learn to see through the tricks and cannot afford to be stupid.”
― Anton LaVey