Presents a simple economic theory explaining how some agriculturally based preindustrial societies (for example, in the Neolithic period) developed despite most of their population being subject to Malthusian dynamics. Their development depended on a dominant class (limited in size) extracting the economic surplus which could be used (among other things) to accumulate capital and advance knowledge and thereby, add to this surplus. Cities facilitated this process. Extraction of the surplus prevented increased population from dissipating it and curtailing development. Several early extractive and non-inclusive societies were long lasting. This is at odds with the theories of some contemporary development economists.