643. In forming this conclusion, apparitions at death are of course selected, because, death being an unique event in man's earthly existence, the coincidences between death and apparitions afford a favourable case for statistical treatment. But the coincidences between apparitions and crises other than death, although not susceptible of the same arithmetical precision of estimate, are, as will be seen, quite equally convincing. To this great mass of spontaneous cases we must now turn.

The arrangement of these cases is not easy; nor are they capable of being presented in one logically consequent series. Each narrative may be regarded from many points of view. There is first of all the nature of the external event, as death or crisis, to which they correspond; there is the mode of their appearance - in dreams, semi-somnolence, or vigilance; there is the special sense (or senses) which they affect - as sight or hearing; and, lastly, there is the effect produced on possible percipients - as their collective perception, by several persons together, or their elective perception by one person only out of several, etc. One of these divisions the distinction of visual and auditory cases - which was fittingly enough employed in arranging the first collection in Phantasms of the Living - may here fall into the background.1 The statistical proportions of visual, auditory, bisensory, and trisensory hallucinations have now been worked out, so far as our materials carry us; and, since we do not suppose that we are concerned with ocular sight or with aural audition, it becomes a minor question which inner sense in each special percipient is most easily stimulated; or, I ought to add, which inner sense each special agent can most easily stimulate.

This distinction, at least, with many others, can conveniently be discussed à propos of individual cases; while the basis of our general arrangement should be found in some more fundamental character.

Now one advantage of the conception of psychical invasion or excursion on which I have already dwelt is that it is at any rate sufficiently fundamental to allow of our arrangement of all our recorded cases - perhaps of all possible cases of apparition - in accordance with its own lines. And even though there be many cases for which the metaphor of invasion seems needlessly strong, and the older metaphor of "telepathic impact" quite sufficient, yet these cases also, although in some sense less complete, will arrange themselves naturally in the same divisions.

Let us take A for the "agent," or the spirit supposed in each case to be invasive or excursive: P for the " percipient," the spirit which plays the more passive role, receiving and sometimes observing the visit of A. Naturally the agent is often - perhaps in reality always - a percipient also. He goes forth to acquire information as well as to give it; but his subliminal self, which makes this excursion, cannot always report the results to his supraliminal self - from whom we outsiders are forced to make our inquiry. His power of giving us information, indeed, is, as we shall see, particularly liable to be cut short by his death.

We want, then, a scheme which is to include, on the lines of this conception of invasion or excursion, all observable telepathic action, from the faint currents which we may imagine to be continually passing between man and man, up to the point - reserved for the following chapter - where one of the parties to the telepathic intercourse has definitely quitted the flesh. The first term in our series must be conveniently vague; the last must lead us to the threshold of the spiritual world.