ABSTRACT
It is two hundred and ®fty years since Montesquieu wrote his `Lettre aÁ William Domville'. In that celebrated essay Montesquieu discussed what would now be called the welfare implications of international trade. The chief novelty of the essay lay in its focus on the wellbeing not of the Prince but of the People, that is, the population at large. The central questions suggested by it concern the sense in which a country may be said to bene®t from the opportunity to trade with other countries and the variety of circumstances under which trade is indeed bene®cial. The ®rst of these questions was answered, although not to everyone's satisfaction, by Vilfredo Pareto (1894), at the end of the nineteenth century. The second question, at the beginning of the twenty ®rst century, still awaits a complete answer.
