Founder of the German Historical School, Roscher (1817-1894) argued a cyclical "stages" theory of historical evolution as well as for the historical method as a positive and not a normative science. His 1843 book : Grundriss zu Vorlesungen über die Staatswirthschaft nach geschichtlicher Methode (Outlines of lectures on political economy based on the historical method) was the definitive methological treatise for the Historical School, where the methodological principles were laid down. Following Hegel, Roscher disparaged the idea of universal theoretical systems - arguing that economic behavior and thus economic "laws" were contingent upon their historical, social and institutional context. To derive any economic "laws", the he argued, the method is thus inevitably cross-disciplinary: one must look at economic life with the eye of a historian and sociologist, as well as an economist. Hence the first task would be essentially that of combing through history for economic details in order to arrive at some idea of what this relationship between the social and economic organization of society might be. In 1848 Roscher became a professor of political economy at the University of Leipzig and started to work on writing his : System der Volkswirthschaft (Principles of political economy), first published in 1854, a work he kept expanding and revising right up to the year of his death in 1894. It became probably the most widely-read textbook of economics in Germany in the second half of the 19th century. This is the fifteenth edition of the first volume on the basic principles of political economy. Blaug : Great economists before Keynes (1986).