Lacan did not endorse the concept of « borderline ». He was opposed to it out of a determination not to yield on the need to account for structure – neurotic, psychotic or perverse. However, the phenomenology of borderline states is encountered more frequently nowadays. Might there be a fourth structure ? In discussing this, I referred to ordinary perversion, but also to the subject in limbo, or to merversion [tr. : a neologism, creating a double play on words : perversion/ père (father), merversion/mère (mother)], and later, to an economy of the hinterland. In that case, wouldn’t it still be a neurosis, though one which is no longer father-centered ? Therefore, the neurosis slanted only to the maternal side – which, remember, is not the center – would be privileged, and what is highlighted is not a new psychic economy in the sense of a radical change, but a neurosis which looks quite different. A series of consequences ensues, which remain to be clarified.