We have now briefly surveyed a series of disintegrations of personality ranging from the most trifling _idée fixe_ to actual alternations or permanent changes of the whole type of character. All these form a kind of continuous series, and illustrate the structure of the personality in concordant ways. There do exist, it must be added, other forms of modified personality with which I shall not at present deal. Those are cases where some telepathic influence from outside has been at work, so that there is not merely dissociation of existing elements, but apparent introduction of a novel element. Such cases also pass through a long series, from small phenomena of motor automatism up to trance and so-called possession. But all this group I mention here merely in order to defer their discussion to later chapters. The brief review already made will suffice to indicate the complex and separable nature of the elements of human personality. Of course a far fuller list might have been given; many phenomena of actual insanity would need to be cited in any complete conspectus. But hysteria is in some ways a better dissecting agent than any other where delicate psychical dissociations are concerned. Just as the microscopist stains a particular tissue for observation, so does hysteria stain with definiteness, as it were, particular synergies--definite complexes of thought and action--more manifestly than any grosser lesion, any more profound or persistent injury could do. Hysterical mutism, for instance (the observation is Charcot's[27]), supplies almost the only cases where the faculty of vocal utterance is attacked in a quite isolated way. In aphasia dependent upon organic injury we generally find other word-memories attacked also,--elements of agraphy, of word-blindness, of word-deafness appear. In the hysteric the incapacity to speak may be the single symptom. So with anæsthesiæ; we find in hysteria a separation of sensibility to heat and to pain, possibly even a separate subsistence of electrical sensibility. It is worth remarking here that it was during the hypnotic trance, which in delicacy of discriminating power resembles hysteria, that (so far as I can make out) the distinctness of the temperature-sense from the pain-sense was first observed. Esdaile, when removing tumours under mesmerism in Calcutta, noticed that patients, who were actually undergoing capital operations without a murmur, complained if a draught blew in upon them from an open window.