" Let's imagine we're virtual particles. We pop into existence and have to decide what to do in our all-too-brief lifetime. (That's not so hard to imagine.) We sniff around. Suppose there's a positively charged particle in the region. If we're negatively charged, we find that particle attractive and try to snuggle up to it. If we're positively charged, we find that other particle repulsive, or at least competitive and possibly intimidating, and we move away. (Neither is that.) "

― Frank Wilczek , The Lightness of Being: Mass, Ether, and the Unification of Forces