§ 1. We have briefly surveyed hallucinations in their more general aspects. But before concentrating our view exclusively on the peculiar telepathic species, we shall do well to pause for a little at an important sub-genus to which that species belongs, but of which it forms numerically only a small part - namely, transient hallucinations of the' sane.

These hallucinatioms, of course, like all others, are the creation of a mind in an abnormal state; but the abnormality may arise in two very different ways. In the large majority of cases it is purely subjective and in some sense pathologic; and the percepts have no objective basis at all outside the perceiving organism. In a comparatively small residue of cases the abnormality is not pathologic or subjective, but consists (it is maintained) in an impression or impulse transferred from another mind. The percepts still conform perfectly to my definition of a sensory hallucination, in lacking the objective basis which they suggest; for that basis would be the actual physical presence of some human body, with its weight, its power of setting the air in vibration by the breath and vocal cords, and all its other attributes. But an objective basis of another sort they have - namely, the exceptional condition of the person whom they recall or represent. Now, having regard to these facts of origin, we might fairly expect that a careful comparison of the purely subjective and the telepathic experiences would reveal a large amount of resemblance, but also a certain amount of difference, between them.

And in no way can we better approach the telepathic or "veridical" class than by following out this comparison.

The available material for the task is, unfortunately, far from abundant; for the purely subjective hallucinations of the sane have met with singularly little attention from psychologists. Here and there a medical man, or a writer of repute, has been led to make some observations by finding a "subject" in himself; a few cases of very marked abnormality, where the phenomena have been recurrent and distressful, have become celebrated - students of the literature get to dread the very names of Nicolai and "Mrs. A."; and the hypnotic cases have an interest of their own, owing to the important place which hypnotism is fast taking in mental science. But no attempt, so far as I know, has been made to obtain wide statistics of perfectly casual cases - of hallucinations in which, if they are still technically pathologic, the abnormality has been of the slightest and most transient kind. The collection which I have formed during the last few years, numbering more than 500 cases, is at any rate large enough to support certain general conclusions.

§ 2. And first, as regards the bodily and mental condition of the percipient. Probably the common view of the hallucinations of the sane, so far as they are recognised at all, is that they are in all cases due to disease or morbid excitement, or at the very least to indigestion. Ask the first twenty rational men you meet how they would account for a phantasmal visitant if they themselves saw one: as many as ten perhaps will answer, "I should conclude that I had dined or supped too well." "Lobster-salad" is an explanation which I have personally heard suggested many times. It may be at once noted, then, as a point of interest - one, moreover, in which the casual and the telepathic classes completely agree - that in not a single instance known to me has the hallucinated person, according to his own account, been suffering at the time from indigestion. Lobster-salad is the parent of nightmares, of massive impressions of discomfort and horror; not, however, as a rule, even in dreamland, of the distinct and minute visualisation, and the clear-cut audition, which constitute the more specific hallucinations of sleep; and certainly not of waking hallucinations.

Nor is morbid excitement of a more general sort a frequent, though it is an occasional, condition; and the same may be said of the ordinary nervous exhaustion that follows hard work. We have only to recall that the commonest occasions of all for delusions of the waking senses are the moments or minutes that immediately follow a night's rest (p. 253). For the majority of cases, the only rule that can be laid down as to the nature of the peculiar disturbance involved is a negative one - that it is not observably connected with any morbid state. Thus the one of my informants who has had perhaps the most interesting experiences of subjective hallucinations, says, "It is when I am at my best physically, and when my mental faculties are keenly interested in something, that the pictures are most frequent and vivid. They are mostly quite the antipodes of my mental occupation."A gentleman who has repeatedly had the hallucination of hearing his name called, tells me that this has always occurred during his holidays, when he was specially well and taking much exercise.

And out of 489 visual and auditory cases (waking and "borderland "), I find that only 24 occurred to persons who were in a decidedly abnormal physical state - ill, or fainting, or overtired, or under anaesthetics.1 Certain exceptional though slight derangement there must undoubtedly be; but the hallucination itself is usually the only symptom of it; and as little in the purely sub- * jective as in the telepathic class can we lay our finger on any special predisposing condition.

The puzzle is the greater in that the phenomenon of waking hallucination in a sane and healthy subject (as the numbers to be presently given will show) is a rare one - rare not merely in the sense of occurring to only a small percentage of the population, but in the sense of occurring to most of these only once or twice in a lifetime. One would have expected that any state of the brain which was liable to occur at all without assignable provocation, would be liable to occur repeatedly. We should account it, for instance, a very odd fact if a person had had one or two extremely distinct dreams in his life, and had had no other experience whatever of dreaming. But we can only take the statistics as we find them. And this peculiar rarity of purely subjective hallucinations of the senses at any rate helps to explain a similar peculiarity in the telepathic class. Our telepathic evidence will show that the hallucination which the percipient describes is as a rule the single and unique instance in his experience.