To understand a science it is necessary to know its history.

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.

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

Humanity is always made up of more dead than living.

Induction for deduction, with a view to construction.

Every science consists in the coordination of facts; if the different observations were entirely isolated, there would be no science.

Ideas govern the world, or throw it into chaos.