In his voluminous treatise De la connoissance de soi-mesme, the Cartesian Benedictine Francois Lamy makes several references to musical experience and to the relationship between music, poetry and rhetoric. The philosopher's investigation is both at the level of moralist analysis and that of description of neurophysiological processes. However, behind the condemnation of the effects of music and the dangerous passionate dynamics it triggers, Lamy's work outlines a general reflection on the "accessory ideas" and the "deaf" and "clandestine" thoughts that escape the subject's consciousness.