The aim of the author is to follow Bion’s lead by addressing the question of knowledge — how we know what we claim to know — in psychoanalysis as a different sort of knowledge. The “sense” that the psychoanalyst uses to detect the object of his study — another mind or personality — is not mechanical. It is his own personality, acting as “a sensory organ for the perception of psychic qualities,” in Freud’s words. The “sense” for detecting this animate unconscious psychic reality is not our mechanical sense organs but what Bion calls the analyst’s O — his own unconscious psychic reality, acting as a receptor for the patient’s projective identifications. He develops the concept of interactional syncrony (Condon). The unique relationship in psychoanalysis between our knowledge (K) and the thing we have knowledge about (O) means that if the acquisition of knowledge is always scientific, as Bion maintains, then a science of psychoanalysis must have a logical structure — a “geometry,” as Bion put it.