If you can’t explain it to a six year old, you don’t understand it yourself.

If you tell the truth, you don’t have to remember anything.

Be alone, that is the secret of invention; be alone, that is when ideas are born.

Two things are infinite: the universe and human stupidity; and I’m not sure about the universe.[Also known as:]Two things are infinite, as far as we know – the universe and human stupidity.

The poor man must walk to get meat for his stomach, the rich man to get a stomach to his meat.

You can get everything in life you want if you will just help enough other people get what they want.

Imperfection is beauty, madness is genius and it’s better to be absolutely ridiculous than absolutely boring.

Truth is everybody is going to hurt you: you just gotta find the ones worth suffering for.

Science, which brings man nearer to God.[Also known as:]Science brings men nearer to God.[La science qui rapproche l’homme de Dieu.]

When people agree with me I always feel that I must be wrong.

Not joy but joylessness is the mother of debauchery.[Die Mutter der Ausschweifung ist nicht die Freude, sondern die Freudlosigkeit.]

History can be well written only in a free country.[Pour bien écrire l’histoire, il faut être dans un pays libre.]