A lily pond, so the French riddle goes, contains a single leaf. Each day the number of leaves doubles—two leaves the second day, four the third, eight the fourth, and so on. Question: If the pond is completely full on the thirtieth day, when is it half full? Answer: On the Twenty-ninth day. The global lily pond in which four billion of us live may already be half full. Although UN projections show world population continuing to grow until it reaches ten to sixteen billion, Lester Brown believes this is unrealistic. In this fascinating analysis of the fisheries, forests, grasslands, and croplands—the author shows that the demands at current levels of population and per capita consumption often exceed the long-term carrying capacity. He documents the overfishing, deforestation, and overgrazing that are gradually undermining human life support systems. He also explains that with energy shortages anticipated in the early eighties and a projected downturn in world oil production in the early eighties and a projected downturn in world oil production in the early nineties, the world must quickly shift to renewable energy resources.