One hot day last summer I was watching a trail of ants in the back yard, marveling at their disciplined and orderly behavior. They marched in a steady line, bunching up occasionally behind an obstacle, but always in perfect unison. Another line flowed in the opposite direction, returning to the nest. Then I had one of those curious moments when the mind superimposes one image upon another. I was looking down at the Long Island Expressway from a plane taking off from the local airport, marveling at an almost identical exhibition of discipline, order, and inscrutable purpose. Thousands of cars ran in steady lines from east to west, bunching up occasionally behind some obstacle, but always in perfect unison. Another line flowed in the opposite direction, returning to the suburban nest. It’s an inescapable fact that aliens viewing Los Angeles or New York from outer space would inevitably assume that we are ants, or something very like. But we know better. The ants, are simply and