It is at any rate impossible, from the record, to be quite sure that adequate means were taken to exclude this hypothesis, which, as Mr. Pollock has recently informed me, is the one that he is now inclined to adopt.

These considerations will certainly suffice to explain the majority of the collective apparitions on record. The visions seen during battles, such as are especially frequent in the history of the Crusades - either signs in the heavens or phantom champions - may easily have had some objective basis. The streak of cloud, which at one moment may be "very like a whale," might at another be equally like a fiery sword; real horsemen might be unrecognised, and the first breath of rumour that they were supernatural assistants would be caught up with avidity.1 More deceptive cases, however, occur, which are not illusions, but yet have as little claim as the preceding to be called collective hallucinations, if that word be (as throughout this treatise it is) confined to the strict sensory meaning. Nothing, for instance, could better illustrate what collective hallucinations are not, than two cases which Dr. Brierre de Boismont2 has adduced to illustrate what they are. A battalion of infantry, after a 40 miles' march under a June sun, was quartered for the night in a dismal building which had the reputation of being haunted.

The surgeon of the regiment describes how, about midnight, these soldiers rushed out of their quarters with wild cries, and declared that the devil had entered their chamber "in the form of a large black dog with curly hair, who had bounded upon them, ran over their chests with the rapidity of lightning, and disappeared on the side opposite to the one at which he had entered." Now - on the supposition that no real dog or cat had a share in shaping the idea - what can be more likely than that the general nervousness took sudden form from one man's sudden cry, on waking from a nightmare? There is not the slightest proof that all present simultaneously saw the dog, and followed his movements. I have already drawn attention to the ease with which uneducated persons may slip into believing that they have seen what they have only heard of; and under excitement this is, of course, doubly easy. One man may have believed that he saw; the rest may merely have believed they had seen. De Boismont's second case is that of Dr. Pordage's disciples in the middle of the seventeenth century, who saw " the powers of hell pass in review before them, seated in chariots, surrounded by dark clouds, and drawn by lions, bears, dragons, and tigers.

These were followed by inferior spirits, who were provided with the ears of a cat or a griffin, and with deformed and distorted limbs." But here the fact that "it made no difference whether their eyes were open or shut " renders it doubtful how far the impression was really more than a vivid inward picture; and there is nothing to contradict, and everything to suggest, the notion that one person described his impressions in language which would easily conjure up the general scene in kindred and excited minds.

1 The reader will recall the phantom battle in the sky, described by Motley (The Rise of the Dutch Republic, pp. 559-60), as to which the depositions of five witnesses were taken on oath. The collective vision of an army marching on terra firma, described by the Duke of Argyll in Good Words for Jan.. 1875, would be less easy to account for as an illusion: but the record is second-hand, and was not written down till more than 50 years after the incident is alleged to have occurred. Phantom champions are not yet extinct. Mr. J. T. Milward Pierce, of Bow Ranche, Nebraska, U.S.A., has told me of a quite recent case, narrated to him by one of the witnesses - where the form of a defunct Indian Chief, "Brown Bear," led his tribe in a battle against the Dacotahs. Mr. Pierce has since sent me a first-hand account of the incident from another professed witness. [For instances stated to have occurred in the present war see S.P.R. Journal for Dec, 1915, especially pp. 115, 116. - ED].

A recent case of a more ordinary type is the following, from Mrs. Lane, of 49, Redcliffe Square, S.W. When at school, she was sleeping in the bed of a Miss Winch, who had been sent home ill; and. waking up, she was much alarmed to see this girl standing at the foot of the bed. She addressed the figure, which nodded slowly. She then roused her companions, "and they all said they saw Miss Winch., too." The girls did not know, what was learnt next day, that Miss Winch was dying; but even supposing the first percipient's vision to have been telepathic, her terrified words, and the dim light, would probably be quite sufficient to convert a bed-hanging or a curtain into the suggested form for her companions1 eves.

2 Des Hallucinations (Paris, 1862), pp. 280, 396.

But apart from such spurious types, cases undoubtedly remain of really externalised collective hallucination, which are still perfectly explicable without resorting to thought-transference. The history of religious epidemics supplies instances where a whole group of persons have professed to behold some exciting or adorable object, and probably actually projected its image into space as part of the surrounding world; but where, without proof (which has never been presented) that what was seen was independently observed and described, it would be rash to suppose any other cause for the similarity of the individual experiences than a previous common idea and common expectancy.1 Nor is even expectancy a necessary condition; there are cases where the suggestion of the moment seems sufficient. The most marked of these are hypnotic hallucinations: it is as easy for a mesmerist to persuade a group of good "subjects "that they all see a particular phantasmal object, as to persuade one of them that he sees it. And I think it must be admitted as possible that mere verbal suggestion may act similarly on certain minds at certain times, without the preliminary of any definite hypnotic process.