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

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

“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.”

“False conclusions which have been reasoned out are infinitely worse than blind impulse.”

“Accuracy of observation is the equivalent of accuracy of thinking.”

“Scepticism does not abolish the world, it turns it into questions.”

“All things must be examined, debated, investigated without exception and without regard for anyone's feelings.”

“When analytic thought, the knife, is applied to experience, something is always killed in the process.”

“You don't kill your way to peace.”

“Thinking is the most overrated human activity.”