This supposition is supported by numerous observations on somnambulists. I will mention only Binet's[110] experiments, where little letters or some such thing, or little complicated figures in relief were laid on the anæsthetic skin of the back of the hand or the neck, and the unconscious perceptions were then recorded by means of signs. On the basis of these experiments he came to the following conclusion: "D'après les calculs que j'ai pu faire, la sensibilité inconsciente d'une hystérique est à certains moments _cinquante fois_ plus fine que celle d'une personne normale." A second additional creation coming under consideration in our case and in numerous other somnambulists, is that condition which French investigators call "cryptomnesia."[111] By this term is meant the becoming conscious of a memory-picture which cannot be regarded as in itself primary, but at most is secondary, by means of subsequent recalling or abstract reasoning. It is characteristic of cryptomnesia that the picture which emerges does not bear the obvious mark of the memory-picture, is not, that is to say, bound up with the idiosyncratic super-conscious ego-complex.
Three ways may be distinguished in which the cryptomnesic picture is brought to consciousness.
1. _The picture enters consciousness without any intervention of the sense-spheres (intra-psychically)._ It is an inrushing idea whose causal sequence is hidden within the individual. In so far cryptomnesia is quite an everyday occurrence, concerned with the deepest normal psychic events. How often it misleads the investigator, the author or the composer into believing his ideas original, whilst the critic quite well recognises their source! Generally the individuality of the representation protects the author from the accusation of plagiarism and proves his good faith; still, cases do occur of unconscious verbal reproduction. Should the passage in question contain some remarkable idea, the accusation of plagiarism, more or less conscious, is justified. After all, a valuable idea is linked by numerous associations with the ego-complex; at different times, in different situations, it has already been meditated upon and thus leads by innumerable links in all directions. It can therefore never so disappear from consciousness that its continuity could be entirely lost from the sphere of conscious memory. We have, however, a criterion by which we can always recognise objectively intra-psychic cryptomnesia. The cryptomnesic presentation is linked to the ego-complex by the minimum of associations. The reason for this lies in the relation of the individual to the particular object, in the disproportion of interest to object. Two possibilities occur: (1) The object is worthy of interest but the interest is slight in consequence of dispersion or want of understanding; (2) The object is not worthy of interest, consequently the interest is slight. In both cases an extremely labile connection with consciousness arises which leads to a rapid forgetting. The slight bridge is soon destroyed and the acquired presentation sinks into the unconscious, where it is no longer accessible to consciousness. Should it enter consciousness by means of cryptomnesia, the feeling of strangeness, of its being an original creation, will cling to it because the path by which it entered the subconscious has become undiscoverable. Strangeness and original creation are, moreover, closely allied to one another if one recalls the numerous witnesses in _belles-lettres_ to the nature of genius ("possession" by genius).[112]