Quote by Descartes, René

"I think, therefore I am."

"The greatest minds are capable of the greatest vices as well as of the greatest virtues."

"Doubt is the key to knowledge."

"If you would be a real seeker of truth, it is necessary that at least once in your life you doubt, as far as possible, all things."

"Hard work never killed anybody."

"Work with purpose and integrity."

"Hard work pays off in the end."

"A man's gotta do what a man's gotta do."