In that wide field of psychopathic deficiency where Science has demarcated the diseases of epilepsy, hysteria and neurasthenia, we meet scattered observations concerning certain rare states of consciousness as to whose meaning authors are not yet agreed. These observations spring up sporadically in the literature on narcolepsy, lethargy, automatisme ambulatoire, periodic amnesia, double consciousness, somnambulism, pathological dreamy states, pathological...