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

Every attempt to employ mathematical methods in the study of chemical questions must be considered profoundly irrational and contrary to the spirit of chemistry.... if mathematical analysis should ever hold a prominent place in chemistry -- an aberration which is happily almost impossible -- it would occasion a rapid and widespread degeneration of that science.

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

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

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

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

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