Religion is an attempt to get control over the sensory world, in which we are placed, by means of the wish-world, which we have developed inside us as a result of biological and psychological necessities... If one attempts to assign to religion its place in man's evolution, it seems not so much to be a lasting acquisition, as a parallel to the neurosis which the civilized individual must pass through on his way from childhood to maturity.

What progress we are making. In the Middle Ages they would have burned me. Now they are content with burning my books.

To endure life remains, when all is said, the first duty of all living being Illusion can have no value if it makes this more difficult for us.

No, our science is no illusion. But an illusion it would be to suppose that what science cannot give us we can get elsewhere.

My love is something valuable to me which I ought not to throw away without reflection.

I consider it a good rule for letter-writing to leave unmentioned what the recipient already knows, and instead tell him something new.

Now it is nothing but torture.