The thesis of Jane Jacobsʹ The Economy of Cities remains remarkably fresh and provocative three decades later. Cities, she asserts, are not the result of processes most scientists and economists have assumed they were: Cities do not develop because a pre-existing rural economic base develops and eventually becomes strong enough to support an essentially parasitic urban growth. Instead, Jacobs argues, cities are the prerequisite for any kind of rural economy. Where there are no cities, there are no sustainable rural economies, and the rural economy depends on the city rather than the other way around. Jacobs defines "city" as a "settlement that consistently generates its economic growth from its own local economy"; population centers of any size that have never done this do not meet her definition of city. Likewise, Jacob defines "urban" as "pertaining only to cities ..."--Review from http://classes.seattleu.edu/multidisciplinary/urbanstudies/resource/reviews/economy.htm (Oct. 18, 2012).