The free association method was designed to shed light on the sexual aetiology of neuroses. Is it equally appropriate for borderline states and Oedipal organizations weakened by the upsurge of perverse sexual polymorphism of infantile origin? Today, there is a tendency to downplay the importance of sexuality, despite the fact that listening to and interpreting psycho-sexuality provides privileged access to the archaic anxieties that are a corollary of the primary relationship with the maternal object. Hypotheses are put forward on how to link the interpretation of the sexual and that of archaic anxieties, as well as on the presence of splitting in repression. Between 1894 and 1901, Freud showed that access to traumatic sexual scenes always conceals another trauma: associative chains are just as polymorphous as infantile sexuality. In conclusion, the analysis of an adolescent girl illustrates the contemporary way of flexibly combining a calming containing capacity and a symbolic interpretation of the sexual in the transference.