In the parallel visual cases, the impression is, at any rate, often of the most distinctive and unmistakable kind; and it is impossible not to be struck by the number of instances in which this startling experience - the single visual hallucination of a person's life - has represented the figure of a friend or relative who was on his way to the place where his figure appeared, and whose mind was probably to some extent picturing his own arrival. None the less, I think, if expectancy existed on the percipient's part, must it be assumed to have been the sufficient cause of the hallucination. Such a case as the following, sent to us by the Rev. F. R. Harbaugh (Pastor of the Presbyterian Church), Red Bank, Monmouth Co., New Jersey, U.S.A., is very instructive.

"February 7th, 1884.

"While a resident of the city of Philadelphia, I made an appointment to meet a personal friend. At the appointed hour I was at the designated place. My friend was tardy in his appearing. After a while, however, I saw him approaching (or thought I did). So assured was I of his advance that I advanced to meet him, when presently he disappeared entirely.

"The locality where I thought I saw his approach was open, and unobstructed by any object behind which he could have disappeared. Only by leaping a high brick wall (an enclosure of a burying-ground) could he have secreted himself. The hallucination was complete - so distinct as to lead me to advance to meet him without a thought of optical illusion.

"I immediately went to the office of my friend, and there learned from him that he had not been away from his desk for several hours.

"F. R. Harbaugh." In answer to an inquiry, Mr. Harbaugh adds: -

"The appointment was forgotten by my friend, as he stated in his apology when I entered his office".

Telepathy from an unconscious region of the defaulter's mind would scarcely be a plausible explanation of this occurrence.

At first sight it may perhaps seem strange that the ordinary everyday sort of expectancy which existed in these cases should be a sufficient cause for so rare and startling a delusion. But remembering that in the majority of startling delusions of the sort there is no assignable cause at all, and that a person may therefore be on the very verge of hallucination without knowing it, we may not unreasonably suppose that a very slight ostensible cause might give the final impulse. It must be noticed, moreover, that in these arrival-cases the alternative to the hypothesis of the subjective origin of the hallucination is by no means clear. For what would the telepathic explanation involve? That on the agent's part the mere sense of being about to arrive, with thoughts perhaps affectionately turning to the percipient, is adequate to generate a telepathic impulse. Now have we any right to make such an assumption?

§ 8. This question, it will be seen, brings us round to the head of ambiguity numbered 1 in the above list; - where the doubt was whether a supposed agent's condition is abnormal enough for a synchronous hallucination of the percipient to form with it a coincidence deserving of attention. And it happens that it is only in the arrival-cases that this question has practically been difficult to decide. Many individual incidents of other types have, of course, been excluded from our evidence, on the ground that the abnormality of the alleged agent's condition was only slight, or that it was prolonged over a considerable time; but these arrival-cases seem to form a distinct little class of their own. It happens also that some of them have presented features which tell rather strongly in favour of a telepathic origin. For instance, the vision representing the coming person has included some detail of dress or appearance which the percipient's mind would have been most unlikely to supply; or again, though the person whom the vision represented was actually about to arrive, his arrival was improbable and unexpected, and therefore the vision could not be connected with the percipient's attitude of mind.

Such instances - though forming too small a group to be conclusive - do not seem any longer to be ambiguous in at all the same degree as those before considered, and they may fairly take their place among the positive evidence in a later chapter.l On the other hand - in view of the fact that in the vast majority of the cases where the evidence for telepathy reaches a certain strength, the agent is doing or suffering something much more remarkable than merely returning home - we do not feel that the telepathic explanation can claim any high degree of probability in any arrival-case where the hallucination has not presented some exceptional evidential feature; and accordingly no such case has been admitted in the sequel.

The discussion of these ambiguous cases has not, I hope, been altogether without positive instruction; but it was necessary, if only to clear the way for further examination of the telepathic phantasms. For if the question whether, or in what sense, those phantasms are hallucinations requires us to compare them with other hallucinations of the sane, the comparison must clearly be confined to cases which are certainly subjective, to the exclusion of cases which may conceivably themselves be telepathic.

1 See Chap. xiv., § 7. In § 6 will be found a few cases where even the condition of arrival was lacking, and the coincidence that suggests telepathy depended simply on a peculiarity of dress or aspect.