Nor is it only as a dissecting agent that hysteria can aid our research. There are in hysteria frequent _acquisitions_ as well as _losses_ of faculty. It is not unusual to find great hyperæsthesia in certain special directions--of touch, hearing, perception of light, etc.--combined with hysterical loss of sensation of other kinds. This subject will be more conveniently treated along with the hyperæsthesia of the hypnotic trance. But I may note here that just such occasional quickenings of faculty were, in my view, almost certain to accompany that instability of psychical threshold which is the distinguishing characteristic of hysteria, since I hold that subliminal faculty habitually overpasses supraliminal. These also are a kind of capricious _idées fixes_; only the caprice in such cases raises what was previously submerged instead of exaggerating what was previously emergent. And from this point it is that our inquiries must now take their fresh departure. We in this work are concerned with changes which are the _converse_ of hysterical changes. We are looking for integrations in lieu of disintegrations; for intensifications of control, widenings of faculty, instead of relaxation, scattering, or decay. Suppose, then, that in a case of instability of the psychical threshold,--ready _permeability_, if you will, of the psychical diaphragm separating the supraliminal from the subliminal self,--the elements of emergence tend to increase and the elements of submergence to diminish. Suppose that the permeability depends upon the force of the uprushes from below the diaphragm rather than on the tendency to sink downwards from above it. We shall then reach the point where the vague name of _hysteria_ must give place to the vague name of _genius_. The uprushes from the subliminal self will now be the important feature; the down-draught from the supraliminal, if it still exists, will be trivial in comparison. The content of the uprush will be congruous with the train of voluntary thought; and the man of genius will be a man more capable than others of utilising for his waking purposes the subliminal region of his being. Next in order to the uprushes of genius will come the uprushes of dream. All men pass normally and healthily into a second phase of personality, alternating with the first. That is _sleep_, and sleep is characterised by those incoherent forms of subliminal uprush which we know as dreams. It is here that our evidence for telepathy and telæsthesia will first present itself for discussion. Sleep will indicate the existence of submerged faculty of a rarer type than even that to which genius has already testified.