The fundamental existential question for the borderline/ hysteric patient is not ‘who am I?’ but ‘where am I?’ or perhaps ‘where can I be?’. This paper1 explores this statement with reference to a pivotal clinical experience which changed the author's thinking and theorizing about this state. Case material is presented which focuses on an experience of what the author describes as ‘primal negation’ which gives rise to primitive displacement anxiety and this is proposed as a specific form of primitive mental agony. There is an elaboration of a borderline defence against an unthinkable experience of formless dread which the author conceives as an attempt to construct a sense of a liveable shape. There is a description of an aspect of the analyst's ‘dreaming on behalf of the patient’ and an elaboration of what this came to mean for both analyst and patient.