These cases will at least prove the possibility of such a thing as “experimental apparitions,” and, explain them as we may, they are, at all events, most interesting and significant. They prove the reality of “telepathic phantasms”—of apparitions produced in another by the power of mind. This is, at least, the modern conception of the facts.
TELEPATHIC HALLUCINATIONS
How may the theory be said to work? How can a telepathic impulse from a distant mind cause a picture to appear in space, as it were, before the recipient? Here is the last word of modern science in this direction; here is the theory which has been advanced to explain puzzling cases of this character.
When we look at and see an object, the sight-centers of the brain are roused into activity; unless they are so aroused, we see nothing, and whenever they are so aroused, no matter from what cause, we have the sensation of sight. We see.
But we get no further than this; we do not reason about the thing seen, or analyze; or think to ourselves, “this is a red apple; I like red apples,” etc. No, we only see or perceive the object. All the reasoning about the object takes place in the higher thought-centres of the brain. A diagram will, perhaps, help to make all this clear.
When light-waves coming from the eye, A, travel along the optic nerves, and excite into activity the sight-centers—at B—we have the sensation of sight, as before said. Nerve currents then travel up the nerves, going from B to C, and in these higher centers, they are associated and analyzed, and we then “reflect” upon the thing seen, etc. This is the normal process of sight.
Now, if the eye, or the optic nerves, or the sight-centers themselves become diseased, we still have the sensation of seeing, though there is no material object there; we have ordinary hallucinations of all kinds—delirium tremens, etc. If the sight-centers are stimulated as much as they would be by the incoming nerve stimuli from the eye, we have “full-blown hallucinations.”
Now, it is obvious that one method of stimulating the sight-centers into activity is for a nervous current to come downwards, along the nerves running from C to B. It is probable that something of this sort takes place when we experience “memory pictures.” If you shut your eyes and picture the face of some dear friend, you will be able to see it before you more or less clearly. The higher psychical centers of the brain have excited the sight-centers into a certain activity; and these have given us the sensation of dim, inward sight. If the stimulus were stronger, we should have cases of intense “visualization”; such as the figures which occur in the crystal ball, etc.—they being doubtless produced in this manner.