This paper takes its origin from a problem raised by the complex and much investigated relation between the French neurologist and alienist Jean-Martin Charcot, and the father of psychoanalysis, Sigmund Freud. Charcot and Freud write in the same years about the same psychopathological phenomenon, hysteria. This paper explores two questions: why do they give such a great importance to, respectively, seeing, or eye observation, and hearing, that is, listening to the patient's account; and how is it possible that Charcot's texts, lectures and therapeutic practices abound with images and photographs, while Freud's texts completely lack them. This paper analyzes the writings of Charcot and Freud on hysteria taking into account different forms and practices of scientific objectivity, arguing that as the techniques of the observer changed, new objects for the sciences of the self emerged.