Denis Diderot

"Great thoughts come from the heart."

"There are three ways to become wise: by experience, by imitation, and by reflection."

"The pen is the tongue of the mind."

"Life is neither suffering nor enjoyment: it is serious business, to be entered upon with courage and in a spirit of self-sacrifice."

"Fidelity is the sister of justice."

"The most dangerous madmen are those created by religion."

"In its essence, every true religion is simply an attitude toward life."

"The greatest source of happiness is the ability to contribute to the happiness of others."

"We are free agents, but we are free to obey the laws of nature."

"History is philosophy teaching by examples."

"Truth has no special time of its own. Its hour is now."

"The mind is always the dupe of the heart."

"I am ashamed of my species."

"Genius creates, talent merely executes."

"The source of all false judgment is fear."

"To live is to act."

"Nature is never at a loss; she is always equal to herself."

"Believe nothing unless it works."

"The privilege of acting is conquered through courage."

"Work keeps us from three great evils: boredom, vice, and poverty."

"The first sign of a noble soul is love for humanity."

"Mediocrity does not consist in being moderately talented on all sides; it consists in a certain mediocrity of spirit."

"The world is filled with fools and the foolish are always certain of themselves."

"Man will never be free until the last king is strangled with the entrails of the last priest."

"Skepticism is the first step toward truth."

"The purpose of an author is to instruct or to amuse."

"Nature has made nothing without a purpose."

"I want to speak sense, but it may come out as nonsense."

"Art elevates the spirit and illuminates the mind."

"The most dangerous madness is that of ideas."