Protoplasm, simple or nucleated, is the formal basis of all life. It is the clay of the potter: which, bake it and paint it as hewill, remains clay, separated by artifice, and not by nature from the commonest brick or sun-dried clod.

Better live a crossing-sweeper than die and be made to talk twaddle by a "medium" hired at a guinea a seance.

Science is simply common sense at its best.

Science ... warns me to be careful how I adopt a view which jumps with my preconceptions, and to require stronger evidence for such belief than for one to which I was previously hostile. My business is to teach my aspirations to conform themselves to fact, not to try and make facts harmonize with my aspirations.

The man of science has learned to believe in justification, not by faith, but by verification.

The great thing in the world is not so much to seek happiness as to earn peace and self-respect.

It is because the body is a machine that education is possible. Education is the formation of habits, a superinducing of an artificial organization upon the natural organization of the body.