From Jean Le Rond to D'Alembert: A route enlightened by new archival data

This article reviews the latest biographical investigation on Jean Le Rond d'Alembert (1717–1783). The results presented here were obtained as part of a project that began in 2009 and has continued ever since. The research was undertaken ab initio, meaning that the approach involved reconsidering everything we thought we knew about d'Alembert. Thanks to the careful analysis of unpublished archival data as well as numerous manuscripts found in national and local archives and libraries, it has been possible to correct significant errors in d'Alembert's biography (including elements considered true and reliable for over a century) and to fill in several gaps.