When examining studies of economic performance, trade and political influence are often a key explanatory factor. If trade enriches countries, then it is important to examine the roots of how goods for trade were produced from natural resources. Fernand Braudel introduced geographical investigation as a methodological development in his acclaimed work, The Mediterranean and the Mediterranean World in the Time of Philip II. Essentially, a historian will begin a study by examining the geographic nature of examples in order to assess the resources available for economic development, or to ensure that natural resources play a key role in understanding how certain countries were able to surpass others. Pomeranz focuses heavily on the natural resources of his examples, rightly so too, as his aforementioned focused comparisons meant that he had to be careful that his examples were actually balanced. The natural resource he pays the most attention to is coal, which Pomeranz believes gave Britain an advantage in the Industrial Revolution. He particularly focuses on the difference between the availability of Chinese and British coal, noting that there was very little coal in the Lower Yangtze. He argues that the geographic location of coal in China was an obstacle to growth, as the northwest was a technologically backward region and the region's coal mines suffered from spontaneous combustion. Clearly, Pomeranz's political study is crucial to understanding how China fell behind Britain when the latter diverged. Institutional studies are most effective when examining political influence on economic development. In An Inquiry into the Nature and Causes of the Wealth of Nations, Adam Smith first formulated a "political inquiry" approach when describing the po...... middle of article..... . Change and economic performance, (Cambridge, 1990).Sheilagh C. Ogilvie, Institutions and European commerce: merchant guilds, 1000-1800, (Cambridge, 2011).Prasannan Parthasarathi, Why Europe became rich and Asia did not Didn't Do It: Global Economic Divergence, 1600-1850, (Cambridge, 2011).Kenneth Pomeranz, The Great Divergence: China, Europe, and the Making of the Modern Global Economy, (Princeton, 2000). Karl Popper, The Poverty of Historicism, (London, 1961). Adam Smith, The Wealth of Nations, (London, 1991).Peter Spufford and Wendy Wilkinson, Provisional List of Exchange Rates in 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).