In this paper I describe my theoretical thinking and clinical work with a patient suffering from obsessional thought disorder and differentiate this from obsessive compulsive disorder, by its absence of ritualized behaviour patterns. I base much of my thinking on Freud, but suggest that the constellation on which this pathology is based consists of a physically and/or emotionally absent father coupled with inadequate mothering. This precludes identification with and emulation of father as the bearer of the ego ideal so that patient attempts to regress to narcissistic blissful union with an idealized mother. If the primary loss, separation from mother, cannot be negotiated successfully then any loss is felt to be intolerable. Thus obsessional thinking is developed as a defence against loss, an attempt within the psyche to create a situation where nothing is given up, symbolized by the alternating opposing thoughts which never get resolved.