So far as we know, Earth is the only planet which supports life, and it is the only planet on which we can survive. Our bodies and our minds are fashioned by it. Our hearts resonate with it. There will be little joy for the human spirit if we destroy the natural fabric of Earth with nothing left to do but go shopping. When we imagine the world a century from now, when we look our great grandchildren in the eye and see them smiling back at us because they know we cared for them, we smile too!