politique (translated in English to "political economy") first appeared in France in 1615 with the well-known book by Antoine de Montchrétien, Traité de l’economie politique. Other contemporary scholars attribute the roots of this study to the 13th Century Tunisian Arab Historian and Sociologist, Ibn Khaldun, for his work on making the distinction between "profit" and "sustenance", in modern political economy terms, surplus and that required for the reproduction of classes respectively. He also calls for the creation of a science to explain society and goes on to outline these ideas in his major work, the Muqaddimah. In Al-Muqaddimah Khaldun states, “Civilization and its well-being, as well as business prosperity, depend on productivity and people’s efforts in all directions in their own interest and profit” – seen as a modern precursor to Classical Economic thought. Leading on from this, the French physiocrats were the first major exponents of political economy, although the intellectual responses of Adam Smith, John Stuart Mill, David Ricardo, Henry George and Karl Marx to the physiocrats generally receive much greater attention. The world's first professorship in political economy was established in 1754 at the University of Naples Federico II in southern Italy. The Neapolitan philosopher Antonio Genovesi was the first tenured professor. In 1763, Joseph von Sonnenfels was appointed a Political Economy chair at the University of Vienna, Austria. Thomas Malthus, in 1805, became England's first professor of political economy, at the East India Company College, Haileybury, Hertfordshire. At present, political economy refers to different yet related approaches to studying economic and related behaviours, ranging from the combination of economics with other fields to the use of different, fundamental assumptions challenging earlier economic assumptions. Current approaches Political economy most commonly refers to interdisciplinary studies drawing upon economics, sociology and political science in explaining how political institutions, the political environment, and the economic system—capitalist, socialist, communist, or mixed—influence each other. The Journal of Economic Literature classification codes associate political economy with three sub-areas: (1) the role of government and/or class and power relationships in resource allocation for each type of economic system; (2) international political economy, which studies the economic impacts of international relations; and (3) economic models of political or exploitative class processes. Within the field of political science, there is generally a distinction between international political economy (studied by international relations scholars) and comparative political economy (studied by comparative politics scholars). Public choice theory is a