“Every sentence I utter must be understood not as an affirmation but as a question.[A caution he gives his students, to b...”

“In a republican nation, whose citizens are to be led by reason and persuasion and not by force, the art of reasoning bec...”

“Reason respects the differences and imagination the similitudes of things.”

“We shall require a substantially new manner of thinking if mankind is to survive.”

“Never accept ultimatums, conventional wisdom, or absolutes.”

“I was too busy fighting the river to worry about adjusting my beliefs in accordance to reality.”

“One must either accept some theory or else believe one's own instinct or follow the world's opinion.”

“To think is to ignore the differences, to generalize, to abstract.”

“Looking at small advantages prevents great affairs from being accomplished.”

“Stupidity lies in wanting to draw conclusions.”

“A long habit of not thinking a thing wrong gives it a superficial appearance of being right.”

“This is one of those cases in which the imagination is baffled by the facts.”