So far as my own explanation is concerned, it will be seen that I still place weight on the general condition of temporary or chronic nervous fatigue as the soil on which paramnesia arises--a belief now accepted by most psychologists[241]--and that I think we must search for the clue to the mechanism of the illusion in those dreaming and hypnagogic states in which it most often occurs. As regards a definite explanation of the mechanism we must, in the face of so many ingenious and complicated theories, perhaps still await more general agreement.[242] What I have suggested, and am still inclined to maintain, is that the psychic enfeeblement, temporary or chronic, which is the general preliminary condition of paramnesia, whether or not there is any subjective sensation of increased power, may account for the paramnesia by bringing an externally aroused perception down to a lower and fainter stage on which it is on a level with an internally aroused perception--a memory. Just as in hypnagogic paramnesia the vivid and life-like dream, or internal impression, is raised to the class of memories, and becomes the shadow of a real experience, so in waking paramnesia the external impression is lowered to the same class. Perception is alike dulled in each case, and the immediate experience follows the line of least resistance--this time too carelessly or too prematurely--to join the great bulk of our experiences.
We thus realise how it is that that doubling of experience occurs. The mind has for the moment become flaccid and enfeebled; its loosened texture has, as it were, abnormally enlarged the meshes in which sensations are caught and sifted, so that they run through too easily. In other words, they are not properly _apperceived_. To use a crude simile, it is as though we poured water into a sieve. The impressions of the world which are actual sensations as they strike the relaxed psychic meshwork are instantaneously passed through to become memories, and we see them in both forms at the same moment, and are unable to distinguish one from the other.
In sleep, and in the hypnagogic state, as in hypnosis, we accept a suggestion, with or without a struggle. In the waking paramnesic state we seem to find, in a slighter stage of a like condition, _the same process in a reversed form_. Instead of accepting a representation as an actual present fact, we accept the actual present fact as merely a representation. The centres of perception are in such a state of exhaustion and disorder that they receive an actual external sensation in the feebler shape of a representation. The actual fact becomes merely a suggestion of far distant things. It reaches consciousness in the enfeebled shape of an old memory--