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

Each department of knowledge passes through three stages. The theoretic stage; the theological stage and the metaphysical or abstract stage.

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

The law is this: that each of our leading conceptions-each branch of our knowledge-passes successively through three different theoretical conditions: the Theological, or fictitious: the Metaphysical, or abstract; and the Scientific, or positive.

Know yourself to improve yourself.

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

The only real life is the collective life of the race; individual life has no existence except as an abstraction.