innumerable stimuli. From all sides thousands of impressions come crowding upon the senses of the individual. Each impression with its appropriate receptors has its corresponding system of reactions which, if not modified or counteracted, may end in some harmful or fatal result. It is not of advantage to the organism of a highly complex organization to respond with reactions to all impressions coming from the external environment. Hence, that organism will succeed best in the struggle for existence that possesses some selective, critical inhibitory "choice and will" centres. The more organized and the more sensitive and delicate those centres are, the better will the organism succeed in its life existence. The guardian-consciousness wards off, as far as it is possible, the harmful blows given by the stimuli of the external environment. In man, this same guardian-consciousness keeps on constructing, by a series of elimination and selection, a new environment, individual and social, which leads to an ever higher and more perfect development and realization of the inner powers of individuality and personality.
Under normal conditions man's superior and inferior centres with their corresponding upper, critical, controlling consciousness together with the inferior automatic, reflex centres and their concomitant subconscious consciousness keep on functioning in full harmony. The upper and lower consciousness form one organic unity,—one conscious, active personality. Under certain abnormal conditions, however, the two systems of nerve-centres with their corresponding mental activities may become dissociated. The superior nerve-centers with their critical, controlling consciousness may become inhibited, split off from the rest of the nervous system. The reflex, automatic, instinctive, subconscious centres with their mental functions are laid bare, thus becoming directly accessible to the stimuli of the outside world; they fall a prey to the influences of external surroundings, influences termed suggestions. The critical, controlling, guardian-consciousness, being cut off and absent, the reduced individuality lacks the rational guidance and orientation, given by the upper choice and will-centres, becomes the helpless plaything of all sorts of suggestions, sinking into the trance states of the subconscious. It is this subconscious that forms the highway of suggestions, suggestibility being its essential characteristic. The subconscious rises to the surface of consciousness, so to say, whenever there is a weakening, paralysis, or inhibition of the upper, controlling will and choice-centres, or in other words, whenever there is a disaggregation of the superior
