In studying hysteria by means of hypnosis, Charcot placed emphasis on the psychological aetiology of the neuroses. Among his pupils, Freud alone grasped this epistemological turning-point, from which he made his great discoveries. But hysteria and hypnosis still remain today largely unknown. We have not yet elucidated the 'mysterious leap' between the psychological and the somatic for the former, and between the relational and the instrumental for the latter. While psychoanalysts have constantly concerned themselves with hysteria, they have shown a lack of interest in hypnosis after Freud abandoned its practice. According to Freud, thanks to transference, affect would be controlled by cognition, a viewpoint eminently suited to satisfy his rationalistic outlook. Affect, however, remains an unknown realm. The affective relationship has, at all events, acquired an ever-increasing importance in psychoanalysis during the last few years, with the emphasis on the early mother-child relationship. The 'affective locus' remains the basic, as well as the most obscure, element in the hypno-suggestive relationship. The behaviourist approach, which quantifies the 'vertical' dimension in depth, is a limited one. The study of the 'horizontal' dimension of subjective experience represents a new line of research, which may make it possible to distinguish different forms of hypnosis. The understanding of hypno-suggestion may throw light on psychoanalysis, psychotherapy, and the human sciences in general.