In her Mémoires, Mme de Genlis (1746–1830) mentions a very ambitious project when she is already 75 years old: she wants to remake the Encyclopeédie ou Dictionnaire raisonneé des sciences edited by Diderot and d’Alembert. Ambition certainly outruns achievement in Genlis’ case – the encyclopedia remains unfinished and unpublished. The aim of this paper is to elucidate the circumstances of the failure of Genlis’ encyclopedia as well as to reflect upon the methodological challenges encountered by the fact that we deal here with an intended ‘copy’ of an existing encyclopedia, that is the source material’s relation to another source.

First I will explore the importance of an “encyclopedic vision” in Genlis’ work at large. In addition to her encyclopedic project, Genlis is also the author of a (finished) Dictionnaire des Etiquettes, and various thematic reference works and manuals. Particular attention will be paid to Genlis’ desire to communicate the scientific ideas of the philosophers of the Enlightenment to a broader audience. This preliminary reflection will offer a framework to identify the steps Genlis took to try to realize her encyclopedia, including the network of persons with whom she collaborated, and to acquire an understanding of the problems she encountered when trying to remake an encyclopedia that was successful almost 60 years earlier, but which could count on reactions of being old-fashioned and inauthentic during her own time.