Julian Simon would have been impressed by this assessment of energy sustainability for Earth Day 2000. This book meets his criteria for thoughtful discourse. First, it separates problems from non-problems. Second, it recognizes that transitional problems will continuously affect society. Third, it examines the forces that might block or encourage solutions to the problems. And finally, it gathers data to determine whether we are gaining or losing ground. Using this deceptively simple methodology, Simon’s life work has forever changed what is popularly called sustainable development theory.