Lester Brown, "the guru of the global environmental movement" (The Telegraph of Calcutta), argues that, like the Sumerian and Mayan civilizations, our economy is fast destroying its environmental support systems, threatening future generations. The challenge is to restructure the global economy, replacing our fossil fuel-based, automobile-centered, throwaway economy with a new one that is environmentally sustainable. Brown outlines his vision of the new economy. It will be powered not with fossil fuels but with solar and wind energy. Its urban transport systems will be centered not around the automobile but around light rail and the bicycle. It will not be a throwaway economy but will be a reuse/recycle economy with a stable population. And building this new economy represents the greatest investment opportunity in history. There is no middle ground. Either we build an economy that is environmentally sustainable or stay with our existing economy until environmental deterioration leads to economic decline.