When examining studies of economic performance, trade and political influence are often a key explanatory factor. If trade makes countries rich, then it is important to examine the roots of how traded goods were produced from natural resources. Fernand Braudel introduced geographical surveying as a methodological development in his acclaimed work, The Mediterranean and the Mediterranean World in the Age of Philip II. In essence, a historian will begin a study by examining the geographic nature of examples in order to evaluate the resources available for economic development or ensure that natural resources play a key role in understanding how some countries were able to outperform others. Pomeranz focuses a lot on the natural resources of his examples, rightly so too because his targeted comparisons mentioned above forced him to be careful to ensure that his examples were truly balanced. The natural resource he pays most attention to is coal, which Pomeranz believes gave Britain a head start in the industrial revolution. He focuses in particular on the difference between Chinese and British coal availability, pointing out that there was very little of it in the Lower Yangzi. He argues that coal's geographic location in China was an obstacle to growth because the northwest was a technologically backward region and coal mines in the area suffered from spontaneous combustion. Pomeranz's political investigation is evidently crucial to understanding how China fell behind Britain when the latter diverged. Institutional studies are more effective in examining political influence on economic development. Adam Smith's An Inquiry into the Nature and Causes of the Wealth of Nations articulated for the first time a "political inquiry" approach outlining the po...... half of the document...... Economic change and performance , (Cambridge, 1990).Sheilagh C. Ogilvie, European Institutions and Trade: Merchant Guilds, 1000-1800, (Cambridge, 2011). Prasannan Parthasarathi, Why Europe Got Rich and Asia Didn't: Global Economic Divergence, 1600-1850, (Cambridge, 2011).Kenneth Pomeranz, The Great Divergence: China, Europe, and the Making of the Modern World Economy, ( Princeton, 2000).Karl Popper, The Poverty of Historicism, (London, 1961).Adam Smith, The Wealth of Nations, (London, 1991).Peter Spufford and Wendy Wilkinson, Interim Listing of the Exchange Rates of Medieval Europe, ( Peter Spufford, 1977). Max Weber, The Protestant Ethic and the Spirit of Capitalism, (New York, 2001). Chris Wickham, Framing the Early Middle Ages: Europe and the Mediterranean 400-800, (Oxford, 2005). Chris Wickham, Problems in Doing Comparative History, (Southampton, 2005).