What makes economies succeed?

The NY Times discovers incentives:

In parts of modern sub-Saharan Africa, as was true in medieval Europe or the antebellum South, the people who work the fields lack any incentive to improve their yield because any surplus is taken by the wealthy elite. This mind-set changes only when farmers are given strong property rights and discover that they can profit from extra production. In 1978, China began allowing farmers to benefit from any surplus they produced. The decision, most economists agree, helped spark the country’s astounding growth.