"For... small things, there must be something else. There is. We call it the electric interaction (more generally, the electromagnetic interaction), and it arises from an endowment of matter known as the . Standing still, an electrically charged particle throws up an to which other charged particles can respond. Electric or magnetic, charge gives rise to both. Whether we say "electric potential" (because we perceive a charge to be at rest) or "" (because we perceive a charge to be in motion), the difference lies solely in our point of view. The source is one. From the world of mass we descend... into the world of charge, ready to see our most familiar surroundings in a new light. Let there be electric charge."