This cultural-historical reading of Les Liaisons dangereuses (1782) situates it in the context of the 1780s engagement with weights and measures reform in France. The protagonists of the novel resort to a language of weights and measures in order to appraise their world which is fraught with material, sexual and ideological signification. Contemporary discussions of weights and measures often incriminated the seigneurial regime as principal abuser of the system, invoking in the process philosophical connotations of “the just measure” or socially responsible moderation and equity. As well, the human body remained at this time the principal benchmark for constituting the systems of measurement with which the French of the 1780s gauged and appraised their physical and imaginative environments. Hence, Choderlos de Laclos’s famous letter-novel of 1782 provides a telling case study allowing us to determine how far the uniquely resonant universe of contemporary fiction reflects and inflects the metrological concerns of its society as well as potentially suggesting ways in which people still measure and weigh the world atavistically, according to pre-metric and pre-decimal, corporeal means.