How to explain the ambiguous place of psychanalysis in our society? Looking back at the Persans de Montesquieu, an anthropologist explored the Parisian universe of psychanalysis for a decade. He describes not only the background of patients and psysonists in a world with its own rules, but also a key episode in the history of the freudian movement in France (general states of psychanalysis, regulation of the title of psychotherapist, publication of a black book of psychanalysis), the authority of which is now challenged in the name of the science and effectiveness of modern psychotherapies... Thanks to the anthropology of a common location which is falsely familiar and which in most cases gives rise to radical criticism or total enthusiasm, the author questions the rationality of a practice which is ultimately unknown to most of us.