[58] I have already touched on the resonance of a sense-impression when the stimulus has ceased to act (see p. 55).  The remarks in the text hold good of all such after-impressions, in so far as they take the form of fully developed percepts.  A good example is the recurrence of the images of microscopic preparations, to which the anatomist is liable. (See Lewes, Problems of Life and Mind, third series, vol. ii. p. 299.) Since a complete hallucination is supposed to involve the peripheral regions of the nerve, the mere fact of shutting the eye would not, it is clear, serve as a test of the origin of the illusion.

[59] That subjective sensation may become the starting-point in complete hallucination is shown in a curious instance given by Lazarus, and quoted by Taine, op. cit., vol. i. p. 122, et seq. The German psychologist relates that, on one occasion in Switzerland, after gazing for some time on a chain of snow-peaks, he saw an apparition of an absent friend, looking like a corpse.  He goes on to explain that this phantom was the product of an image of recollection which somehow managed to combine itself with the (positive) after-image left by the impression of the snow-surface.

[60] For an account of Mr. Galton’s researches, see Mind, No. xix.  Compare, however, Professor Bain’s judicious observations on these results in the next number of Mind.  The liability of children to take images for percepts, is illustrated by the experiences related in a curious little work, Visions, by E.H.  Clarke, M.D. (Boston, U.S., 1878), pp. 17, 46, and 212.

[61] A common way of describing the relation of the hallucinatory to real objects, is to say that the former appear partly to cover and hide the latter.

[62] Griesinger remarks that the forms of the hallucinations of the insane rarely depend on sense-disturbances alone.  Though these are often the starting-point, it is the whole mental complexion of the time which gives the direction to the imagination.  The common experience of seeing rats and mice running about during a fit of delirium tremens very well illustrates the co-operation of peripheral impressions not usually attended to, and possibly magnified by the morbid state of sensibility of the time (in this case flying spots, muscae volitantes), with emotional conditions. (See Griesinger, loc. cit., p. 96.)

[63] Wundt (Physiologische Psychologie, p. 652) tells us of an insane woodman who saw logs of wood on all hands in front of the real objects.