In 1980, Keith Hopkins presented a general model of the interdependence of movements of taxes, traded goods and money in the Roman empire. This bold attempt to construct a comprehensive explanatory framework for the expansion of market exchange in the wake of Roman conquest attracted considerable attention as well as criticism. One and a half decades later, Hopkins restated and refined his position in an article that took full account of the debate triggered by his original argument. Published in an academic journal of limited circulation, this important contribution is now being made more readily accessible. Hopkins, who held Moses Finley’s chair at Cambridge, stands out among ancient historians for his professional background and research in both classics and sociology. As a social scientist, he has consistently preferred deductivist arguments and comparativist analogy over positivist and inductivist readings of ancient source material. After successfully redefining the terms of the debate in Roman population studies, Hopkins soon turned to the study of the Roman economy, devising sweeping models of urbanisation, the spread of chattel slavery, and the expansion of trade that have left their mark on the field.§