Every so often a maverick knight sets off into the dark forest looking for the Holy Grail of “why isn’t the whole world developed?” In this book, which has the heavy bibliographical armor of the genre and 40 pages of appendices too, John Powelson reports on his quest. He claims to have found in a concept called “power diffusion” a significant part of the answer to two related questions: why did the modem economy first appear in northwestern Europe and Japan, and what characteristics of those regions account for their ability to sustain economic growth? Growth is to him the serendipitous outcome of seemingly unconnected events, and he defines sustained growth as that which lasts a century or more.