Know yourself to improve yourself.

The word right should be excluded from political language, as the word cause from the language of philosophy.

Men are not allowed to think freely about chemistry and biology: why should they be allowed to think freely about political philosophy?

Positivism is a theory of knowledge according to which the only kind of sound knowledge available to human kind is that if science grounded in observation.

The universe displays no proof of an all-directing mind.

Nothing is destroyed until it is replaced.

Religion is an illusion of childhood, outgrown under proper education.