Obsessional certainty belongs to a world of two people only, self and object, from which any third would be excluded. Absolute certainty is a state of mind dominated by an unconscious phantasy in which, from the point of view of the self, the object's mind is transparent; this omniscience is a defence mechanism aimed at maintaining the object as the possession of the self. This excludes both a third object which would threaten this position, and catastrophic uncertainty about being held in mind at all. Absolute doubt is a defence against the more ordinary, though tormenting, uncertainty about what goes on in the object's mind; it is brought about by a sense that the object is mentally not available, that it is opaque. In this formulation, delusional jealousy is a continuous projection onto this opaque object of exciting and tormenting versions of the primal scene.