Sigmund Freud, whose influence is undeniable, needs no introduction. But it is here a less usual face of the psychoanalyst that the general public is invited to discover. To quote Freud himself, there is nothing like a little cocaine to "loosen the tongue": "Such have been my performances (or rather those of cocaine) and I am very satisfied with them." A work that allows us to glimpse the importance of cocaine on the genesis of the theory of the unconscious.