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Rh amount of consciousness, to speak figuratively, may not in all cases be affected, but the level sinks; it includes less of the higher and more of the lower. In various forms of trance, however, and in cases of double personality, the cleavage is commonly vertical. The new consciousness is approximately on the same level as the old. The higher cerebral centres still continue their functions; the new personality is not a mere torso, as in sleep; it is so to speak complete in itself. It is not necessarily either higher or lower, it is merely different. The difference, generally speaking, may be presumed to lie in the inclusion or exclusion of certain sensorimotor areas, the reviviﬁcation or inhibition of certain cerebral tracts, with all the memories and sensations based upon them. The earliest indications of this vertical cleavage, it should be noted, may be traced in the various forms of automatism, beginning with simple reverie, and going on to crystal gazing, table-turning, and automatic writing. In such cases as a rule the control of the primary consciousness is not lost, but a parasitic secondary consciousness, a small dissociated area, has become active on its own account.

Now the feeling of personal identity depends upon the memory of past and the consciousness of present sensations. Any change in these is liable to impair the sense of personality. That sense of personality is not seriously affected in sleep or intoxication, partly because the states are familiar, partly no doubt because the consciousness is not