For all people, life passes through and around us in light and shadow. We enjoy moments of joy and comfort, when no sooner we're faced with upset, disappointment, sometimes even tragedy. The art we create, our music, literature, painting, theatre and the rest, reflects this. Think of Shakespeare, or Rembrandt, or Beethoven, or your favorite lifetime film. Can we appreciate moments of joy, without having known sadness? We see it in nature. The brilliant...