To save the world requires faith and courage: faith in reason, and courage to proclaim what reason shows to be true.

What science cannot discover, mankind cannot know.

Intelligence, it might be said, has caused our troubles; but it is not unintelligence that will cure them. Only more and wiser intelligence can make a happier world

The universe may have a purpose, but nothing we know suggests that, if so, this purpose has any similarity to ours.

Italy, and the spring and first love all together should suffice to make the gloomiest person happy.

Fear is the main source of superstition, and one of the main sources of cruelty. To conquer fear is the beginning of wisdom.

Orthodoxy is the death of intelligence.