Don't believe the results of experiments until they're confirmed by theory.

Electrical force is defined as something which causes motion of electrical charge; an electrical charge is something which exerts electric force.

What we makes of the world must be largely dependent on the sense-organs that we happen to possess. How the world must have changed since the man came to rely on his eyes rather than his nose.

Our model of Nature should not be like a building-a handsome structure for the populace to admire, until in the course of time some one takes away a corner stone and the edifice comes toppling down. It should be like an engine with movable parts. We need not fix the position of any one lever; that is to be adjusted from time to time as the latest observations indicate. The aim of the theorist is to know the train of wheels which the lever sets in motion-that binding of the parts which is the soul of the engine.

I ask you to look both ways. For the road to a knowledge of the stars leads through the atom; and important knowledge of the atom has been reached through the stars.

There is only one law of Nature-the second law of thermodynamics-which recognises a distinction between past and future more profound than the difference of plus and minus. It stands aloof from all the rest. ... It opens up a new province of knowledge, namely, the study of organisation; and it is in connection with organisation that a direction of time-flow and a distinction between doing and undoing appears for the first time.

I don't believe any experiment until it is confirmed by theory. I find this is a witty inversion of "conventional" wisdom.