To a certain limited extent such co-ordination is possible. In each approach to telæsthesia in turn we find a tendency to something like a dream-excursion. Hyperæsthesia, in the first place, although it exists sometimes in persons wide awake, is characteristically an attribute of sleep-waking states. We have seen in discussing hypnotic experiments that it is sometimes possible to extend the subject's perceptive faculty by gradual suggestion, so far as to transform a hyperæsthesia which can still be referred to the action of the sense-organs into a telæsthesia which cannot be so referred. It is observable that percipients in such cases sometimes describe their sensation as that of receiving an impression, or seeing a picture placed before them; sometimes as that of _travelling_ and visiting the distant scene or person. Or the feeling may oscillate between these two sensations, just as the sense of _time-relation_ in the picture shown may oscillate between past, present, and future. To all these complex sensations the phenomena of crystal-gazing offer close analogies. I have already remarked on the curious fact that the simple artifice of gazing into a speculum should prove the avenue to phenomena of such various types. There may be very different origins even for pictures which in the crystal present very similar aspects; and certain sensations do also accompany these pictures; sensations not merely of _gazing_ but sometimes (though rarely) of partial _trance_; and oftener of _bilocation_;--of psychical _presence_ among the scenes which the crystal has indeed initiated, but no longer seems to limit or to contain. The idea of psychical excursion thus suggested must, however, be somehow reconciled with the frequently _symbolic_ character of these visions. The features of a crystal-vision seem often to be no mere transcription of material facts, but an abbreviated selection from such facts, or even a bold modification of such facts with a view of telling some story more quickly and clearly. We are familiar with the same kind of succession of symbolical scenes in dream, or in waking reverie. And of course if an intelligence outside the crystal-gazer's mind is endeavouring to impress him, this might well be the chosen way. And moreover through all telæsthetic vision some element of similar character is wont to run--some indication that _mind_ has been at work upon the picture--that the scene has not been presented, so to say, in crude objectivity, but that there has been some _choice_ as to the details discerned; and some _symbolism_ in the way in which they are presented. Let us consider how these characteristics affect different theories of the mechanism of clairvoyance. Let us suppose first that there is some kind of transition from hyperæsthesia to telæsthesia, so that when peripheral sensation is no longer possible, central perception may be still operating across obstacles otherwise insurmountable.