These preliminary considerations are applicable to any kind of alleged communication from the departed—whether well or ill evidenced; whether conveyed in sensory or in motor form.
Let us next consider what types of communication from the dead our existing evidence of communications among the living suggests to us as analogically possible. It appears to me that there is an important parallelism running through each class of our experiments in automatism and each class of our spontaneous phenomena. Roughly speaking, we may say that our experiment and observation up to this point have comprised five different stages of phenomena, viz., (I.) hypnotic suggestion; (II.) telepathic experiments; (III.) spontaneous telepathy during life; (IV.) phantasms at death; (V.) phantasms after death. And we find, I think, that the same types of communication meet us at each stage; so that this recurrent similarity of types raises a presumption that the underlying mechanism of manifestation at each stage may be in some way similar.
Again using a mere rough form of division, we shall find three main forms of manifestation at each stage: (1) hallucinations of the senses; (2) emotional and motor impulses; (3) definite intellectual messages.
(I.) And first let us start from a class of experiments into which telepathy does not enter, but which exhibit in its simplest form the mechanism of the automatic transfer of messages from one stratum to another of the same personality. I speak, of course, of post-hypnotic suggestions. Here the agent is a living man, operating in an ordinary way, by direct speech. The unusual feature lies in the condition of the percipient, who is hypnotised at the time, and is thus undergoing a kind of dislocation of personality, or temporary upheaval of a habitually subjacent stratum of the self. This hypnotic personality, being for the time at the surface, receives the agent's verbal suggestion, of which the percipient's waking self is unaware. Then afterwards, when the waking self has resumed its usual upper position, the hypnotic self carries out at the stated time the given suggestion,—an act whose origin the upper stratum of consciousness does not know, but which is in effect a message communicated to the upper stratum from the now submerged or subconscious stratum on which the suggestion was originally impressed.
And this message may take any one of the three leading forms mentioned above;—say a hallucinatory image of the hypnotiser or of some other person; or an impulse to perform some action; or a definite word or sentence to be written automatically by the waking self, which thus learns what order has been laid upon the hypnotic self while the waking consciousness was in abeyance.
(II.) Now turn to our experiments in thought-transference. Here again the agent is a living man; but he is no longer operating by ordinary means,—by spoken words or visible gestures. He is operating on the percipient's subconscious self by means of a telepathic impulse, which he desires, indeed, to project from himself, and which the percipient may desire to receive, but of whose modus operandi the ordinary waking selves of agent and percipient alike are entirely unaware.
Here again we may divide the messages sent into the same three main classes. First come the hallucinatory figures—always or almost always of himself—which the agent causes the percipient to see. Secondly come impulses to act, telepathically impressed; as when the hypnotiser desires his subject to come to him at an hour not previously notified. And thirdly, we have a parallel to the post-hypnotic writing of definite words or figures in our own experiments on the direct telepathic transmission of words, figures, cards, etc., from the agent, using no normal means of communication, to the percipient, either in the hypnotised or in the waking state.
(III.) We come next to the spontaneous phantasms occurring during life. Here we find the same three broad classes of messages, with this difference, that the actual apparitions, which in our telepathic experimentation are thus far unfortunately rare, become now the most important class. I need not recall the instances given in Chapters IV. and VI., etc., where an agent undergoing some sudden crisis seems in some way to generate an apparition of himself seen by a distant percipient. Important also in this connection are those apparitions of the double, where some one agent is seen repeatedly in phantasmal form by different percipients at times when that agent is undergoing no special crisis.
Again, among our telepathic impressions generated (spontaneously, not experimentally) by living agents, we have cases, which I need not here recapitulate, of pervading sensations of distress; or impulses to return home, which are parallel to the hypnotised subject's impulse to approach his distant hypnotiser, at a moment when that hypnotiser is willing him to do so.
And thirdly, among these telepathic communications from the living to the living, we have definite sentences automatically written, communicating facts which the distant person knows, but is not consciously endeavouring to transmit.