NEW YORK -- When the new field of political economy emerged in the 18th century, it concerned itself largely with two questions: how societies get rich, and how they can justly divide that wealth. The thinking of this year's winner of the Nobel Memorial Prize in economics, Columbia University professor Edmund Phelps, hews close to that tradition, seeking the roots of prosperity and ways to maintain economic justice -- not only in today's world, but across generations. In choosing Prof. Phelps, the Nobel committee focused on his work in the area of inflation and unemployment. But that isn't all Prof....