After more than a century of relative stagnation, the economies of India and China have been growing at remarkably high rates over the past 25 years. In 1820 the two countries contributed nearly half of the world’s income; by 1950, with the industrialized West having pulled away, their share had fallen to less than one-tenth. Today it is just less than one-fifth, and projections suggest that by 2025 it will rise to one-third. (In 2008 the World Bank is expected to issue revised numbers about cost of living in China and India, which may somewhat reduce these estimated income shares, both current and future).

The consequences of this expansion are extraordinary. The Chinese economy in particular has made the most headway against poverty in world history, with hundreds of millions of people moved out of the most extreme poverty within just a generation. (The environmental consequences are comparably remarkable, though perhaps proportionately disastrous).

What explains this strikingly rapid growth?