For most of humanity the third quarter of the century was a period of unprecedented prosperity. The world's output of goods and services, expanding 4 per cent or more annually, tripled in less than a generation. Growth seemed commonplace—and was soon built into consumer aspirations, corporate earnings projections, and government revenue expectations. Few stopped to calculate that if the 4 per cent rate of economic growth remained steady, there would be a fiftyfold expansion in just a century. And even fewer considered the pressure this would put on the earth's resources.