One night recently I was driving down a two lane highway at about 60 miles an hour. A car approached from the opposite direction at about the same speed. As we passed each other,I caught the other driver's eye for only a second. I wondered whether he might be thinking,as I was,how dependent we were on each other at that moment. I was relying on him not to fall asleep,not to be distracted by a cell phone conversation,not to cross over into my lane and bring my life suddenly to an end. And though we were strangers to each other,he relied upon me in just the same way. Multiplied a million times over,I believe that is the way the world works. At some level we all depend upon one another. Sometimes that dependence requires us simply to refrain from doing something—like crossing over the double yellow line. And sometimes it requires us to act cooperatively,with allies or even with strangers.