This chapter studies money as a fundamental tool in the market process. Money was an agent of social power, but also a tool empowering economic life. Beginning with medieval models of money’s political, social and economic functions, dating back to Oresme’s De Moneta: texts that represent the ‘origins of political economy’, the chapter studies policies and writings on monetary management in the preindustrial world. From the Middle Ages until the 1870s, monetary theories shared common features only given up when the concept of money’s purchasing power was decoupled from its metallic value (since this happened fairly late, during the 20th century, it won’t concern us much). Currency stability and inflation management were known to preindustrial authors and rulers as tools promoting economic development.