Book excerpt: Brown argues that, as with the ancient Mayans, escalating world food demands are leading to topsoil losses that are eroding the foundation of present civilization. Deforestation, overgrazing and overfishing are shrinking the economy's resource base, leading to the biological equivalent of deficit financing. Unremitting inflation indicates that the transition to a sustainable society is behind schedule. Yet Brown finds reason for hope, China has recently halved its population growth rate and U.S. oil imports were cut by a third in two years. There are exciting signs of a shift to renewable energy, endowing the economy with permanence. Unlike the Mayans, today's societies know the course corrections needed to put it on a sustainable path.