§ 1. Phantasms which have affected the senses of more than one percipient, are a specially perplexing class. On the face of them, they suggest a real objective presence of the person seen or heard. But such "objectivity " (unless conceived as some illusive form of matter) can hardly be defined except just as a temporary existence in more minds than one: it does not explain, but merely repeats, the fact that the experience is collective ...... 466-467

In the absence of evidence (worthy of the name) that a telepathic phantasm has ever given a test of physical reality - e.g., by opening a door or a window - we are led to inquire how far the phenomena of collective hallucination can be covered by a theory of purely psychical impressions. Two views (which will subsequently prove capable of amalgamation) present themselves: - (1) that A, at a distance, produces simultaneous telepathic impressions on the minds of B and C, who happen to be together; (2) that B's impression, however originated, passes on to C by a process of thought-transference - the hallucination itself being, so to speak, infectious ......... 467-468

§ 2. The first of these hypotheses presents great difficulties. For our review of telepathic hallucinations, so far, has shown that they may take very various forms, and may be projected at various intervals of time (within a range of a few hours) from the crisis or event to which we trace them; so that, supposing several persons to have been the joint recipients of a telepathic impression, it seems most improbable that they should independently invest it at the same moment with the same sensory form. Nor, again, should we expect to find, among those jointly affected, any person who was a stranger to the distant agent; nevertheless, cases occur where such a person has shared in the collective percipience. And yet again, on this theory of independent affection of several persons, there seems no special reason why they should be in one another's company at the time, since the agent may presumably exercise his influence equally in any direction; nevertheless, cases where the percipients have been apart are, in fact, extremely rare ....... 468-469

A few examples of the sort are given; but in several even of these, the percipients, though not together, were very near one another, and had been to some extent sharing the same life ....... 469-473

§ 3. As to the second of the proposed hypotheses - that one percipient catches the hallucination from another by a process of thought-transference - the question at once suggests itself whether such communicability is ever found in cases where no distant agent is concerned - cases of purely subjective hallucination. Such an idea would, no doubt, be as new to scientific psychology as every other form of thought-transference; but transient hallucinations of the sane have been so little studied or collected that it is not surprising if the evidence for collective experiences of the sort has escaped attention - though collective illusions have sometimes been described as hallucinations . . . 473-474

It is in collective cases that the importance of distinguishing illusions from hallucinations becomes plain. In illusions, the persons affected receive an actual sensory impression from a real object, the error being simply in their way of interpreting it; and in the interpretation they are often greatly at the mercy of one another's suggestions. Many historical incidents - such as visions of signs in the heavens and of phantom champions - might be thus explained 474 - 476

In other alleged instances of "collective hallucination" there is no proof that the impression was really more than a vivid mental picture, evoked under excitement. And even where the image probably has been externalised in space - as, e.g., in religious epidemics, or in experimentation! with hypnotised subjects - most cases may be at once explained, without any resort to thought-transference, as due to a common idea or expectancy. (Apart, however, from special excitement or from hypnotism, the power of mere verbal suggestion to produce delusions of the senses may easily be exaggerated) .... 476-478

It is only when these various conditions are absent - when the joint percept is clearly hallucination, and is also projected by the several percipients without emotional preparation or suggestion - that the hypothesis of thought-transference from one percipient to another can reasonably be entertained . . 478-479

§ 4. The examples to be adduced, of collective hallucinations, not apparently originating in the condition of any absent living person, include cases which may be regarded by some as indicating post-mortem agency. It is not necessary to enter into the vexed question as to whether the power of exercising psychical energy can or cannot continue after physical death. Whatever answer that question received, these cases would still, in the writer's opinion (for reasons set forth in § 2), bear witness to a quite mundane transference between the minds of the living percipients ....... 479-481

§ 5. Visual examples. Hallucinations of light ..... 481

Various out-of-door experiences, not easy to explain as illusions . 481-484

Examples -of the simultaneous appearance of an unrecognised figure to two percipients, who in most instances were in each other's company at the time. The two impressions received in several cases were not precisely similar, and in one (No. 322) were markedly different ...... 484-489

Similar appearances of recognised phantasms; one of which (case 333) represented the form of one of the percipients ..... 489-495

The auditory class requires special care, owing to the liability of real sounds (whose source is often uncertain) to be misinterpreted. Example . 495-496

The examples may at all events show that a purely psychical account of these joint experiences is possible. It is not, indeed, obvious why hallucinations of the senses should be a form of experience liable to transmission from mind to mind; but as regards the cases which are telepathically originated, some explanation may perhaps be found in the fact that they at any rate involve a disturbance of a very peculiar kind ......... 496-497

§ 6. Collective hallucinations of telepathic origin. Auditory examples, representing vocal sounds ........ 497-499

And non-vocal sounds ........ 499-502

Visual examples. In one of these (No. 345) the experiences of the two percipients were not precisely similar ...... 502-513

§ 7. The fact that in most of the examples the two percipients, B and C, were together suggests that mere community of scene, or of immediate mental occupation, may establish a rapport favourable to "psychical" transferences 513-514

And this conception may lead us, in cases where a distant agent, A, is concerned, to an amalgamation of the two hypotheses (see § 1) which have hitherto been treated separately. C's experience, qua hallucination, that is to say in its sensory character, may be derived from B's; but, for all that, A may be telepathically affecting C. It may be A's joint influence on B and C that has conditioned the transference of sensation between them; or, in cases where C holds no intimate relation to A, a rapport may be established, ad hoc, between A and C by the rapport of both of them with B - who thus serves, so to speak, as a channel for C's percipience; and this would even help to explain the cases where B is not himself consciously percipient ...... 514-515

The conception of rapport through community of mental occupation might explain the various cases where the telepathic influence seems to have been locally conditioned, by the presence of the percipient in a place that was interesting to the agent. And the idea may receive a still further extension in cases where there is reason to suppose a reciprocal telepathic clairvoyance of the scene on the agent's part .......... 515-516

Conjectures of this sort concerning the more outlying telepathic phenomena have an air of rashness; but the mere fact that "psychical" transferences are possible, when once admitted, opens up a scheme of Idealism within whose bounds (if bounds there be) the potential unity between individual minds is at any rate likely to realise itself in surprising ways .... 516-517