How could the human mind progress, while tormented with frightful phantoms, and guided by men, interested in perpetuating its ignorance and fears? Man has been forced to vegetate in his primitive stupidity: he has been taught stories about invisible powers upon whom his happiness was supposed to depend. Occupied solely by his fears, and by unintelligible reveries, he has always been at the mercy of priests, who have reserved to themselves the right of thinking for him, and of directing his actions.

It is thus religion infatuates man from his infancy, fills him with vanity and fanaticism: if he has a heated imagination it drives him on to fury; if he has activity, it makes him a madman, who is frequently as cruel to himself, as he is dangerous and incommodious to others: if, on the contrary, he be phlegmatic or of a slothful habit, he becomes melancholy and is useless to society.

When we examine the opinions of men, we find that nothing is more uncommon, than common sense; or, in other words, they lack judgment to discover plain truths, or to reject absurdities, and palpable contradictions.

All religious notions are uniformly founded on authority; all the religions of the world forbid examination, and are not disposed that men should reason upon them.

If the ignorance of nature gave birth to gods, the knowledge of nature is calculated to destroy them.

What, indeed, is an atheist? He is one who destroys delusions which are harmful to humanity in order to lead men back to nature, to reality, to reason. He is a thinker who, having reflected on the nature of matter, its energy, properties and ways of acting, has no need of idealized powers or imaginary intelligences to explain the phenomena of the universe and the operations of nature.

The source of man's unhappiness is his ignorance of Nature.