In the present chapter we revert once more to experimental evidence. The cases now to be discussed should, in the logical order, have been included in Chapter V., and for a proper appreciation of their theoretic bearings and evidential value they ought to be considered in connection with the instances of thought-transference at a distance there recorded. It seemed best, however, to separate these instances of the experimental production of hallucinations at a distance, and reserve them for subsequent treatment, with the view of anticipating as far as possible the misconceptions to which this class of evidence is peculiarly open. In brief, until some attempt had been made to elucidate the nature of sensory hallucination in general, it seemed unwise to introduce matter so controvertible as apparitions of the human figure. For we are here assailing the last fortress of superstition; in discussing such matters even educated persons find it difficult to free themselves from the fetters of traditional modes of thought and speech. Men who would be ashamed to think of earth, air, fire, and water as elements, because they were so held a century ago and are now so styled in the language of the market-place, will often see no middle course between rejecting altogether evidence of the kind here dealt with, and accepting the existence of "ghosts." But those who have followed the argument of the preceding chapters will see, if the possibility of thought-transference is granted, that the narratives now to be presented fall naturally into place as illustrating one of its modes of manifestation. That A. by taking thought should cause an image of himself to appear to B. need provoke no more surprise than that by the same means he should cause B. to see No. 27, or the Queen of Hearts. No one demands a spiritual entity corresponding to the Queen of Hearts, why then should any one believe in the other case that A.'s spirit had left its fleshly tabernacle to interview B.? The hallucinatory figure induced post-hypnotically in certain subjects presents an even closer parallel. It is recognised by all in such a case that the figure seen is a _thought_ fashioned by the subject's mind, with no more substance than any other thought. It is only the influence of an unrecognised animism which leads us to demand such a substantial basis when the figure seen represents a dying man. The impulse which led to the projection of the hallucination was in the one case conveyed by word of mouth, in the other by some process as yet not understood. But the mystery lies in the process rather than in the result.