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

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

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

If we do not allow free thinking in chemistry or biology, why should we allow it in morals or politics?

Language forms a kind of wealth, which all can make use of at once without causing any diminution of the store, and which thus admits a complete community of enjoyment; for all, freely participating in the general treasure, unconsciously aid in its preservation.

The dead govern the living.

In mathematics we find the primitive source of rationality; and to mathematics must the biologists resort for means to carry out their researches.