“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.”

“[T]he vast majority of human beings are not interested in reason or satisfied with what it teaches.”

“The rationalist imagines an imbecile-free society; the empiricist and imbecile-proof one, or even better, a rationalist-...”

“The beginning of thought is in disagreement - not only with others but also with ourselves.”

“How dangerous can false reasoning prove!”

“We only think when we are confronted with a problem.”

“The simplest questions are the most difficult.”

“It takes a very unusual mind to undertake the analysis of the obvious.”