The word reality frightens me.

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

Proof is an idol before which the mathematician tortures himself.

It is also a good rule not to put overmuch confidence in the observational results that are put forward until they are confirmed by theory.

An ocean traveler has even more vividly the impression that the ocean is made of waves than that it is made of water.

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.

An electron is no more (and no less) hypothetical than a star. Nowadays we count electrons one by one in a Geiger counter, as we count the stars one by one on a photographic plate.