Abstract: At the time of Fontenelle, in the Parisian academies, overt discourse and secret thoughts were intermingled. Alongside their official productions, and not unrelated to them, academicians and their friends contributed to the inspiration and dissemination of a resolutely heterodox culture and systems that could only circulate clandestinely. The exceptional collection of the Bibliothèque Mazarine particularly enriches the sociological orientation of research on the clandestine.
