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

“Most people would die sooner than think in fact they do.”

“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.”

“...there is no explaining anything by reasoning and so it is useless to reason.”

“Take away paradox from the thinker and you have a professor.”

“The only means of strengthening one's intellect is to make up one's mindabout nothing -- to let the mind be a thoroughfa...”

“I pass with relief from the tossing sea of Cause and Theory to the firm ground of Result and Fact.”

“One must be sane to think clearly, but one can think deeply and be quite insane.”

“Merely having an open mind is nothing. The object of opening the mind as of opening the mouth is to shut it again on s...”

“It Begins with skepticism. The history of human folly, and our own susceptibility to illusions and fallacies, tell us th...”