Each time history repeats itself, so it's said, the price goes up. The twentieth century was a time of runaway growth in human population, consumption, and technology, placing a colossal load on all natural systems, especially earth, air, and water -- the very elements of life. The most urgent questions of the twenty-first century are: where will this growth lead? can it be consolidated or sustained? and what kind of world is our present bequeathing...