APPARITIONS
The intrusion (as an apparition) of a person or thing into a completely enclosed portion of three-space; or contrariwise, the exit (as an evanishment) out of such a space.
Because we lack the sense of four-dimensional space, we must here have recourse to analogy, and assume three-dimensional space to be the unsensed higher region encompassing a world of two dimensions, To a hypothetical flat-man of a two-space, any portion of his plane surrounded by an unbroken line would constitute an enclosure. Were he confined within it, escape would be impossible by any means known to him. Had he the ability to move in the third dimension, however, he could rise, pass over the enclosing line without disturbing it, and descend on the other side. The moment he forsook the plane he would disappear from two-dimensional space. Such a disappearance would constitute an occult phenomenon in a world of two dimensions.
Correspondingly, an evanishment from any three-dimensional enclosure—such as a room with locked doors and windows—might be effected by means of a movement in the fourth dimension. Because a body would disappear from our perception the moment it forsook our space, such a disappearance would be a mystery; it would constitute an occult phenomenon. The thing would be no more mysterious, however, to a consciousness embracing four dimensions within its ken, than the transfer of an object from the inside to the outside of a plane figure without crossing its linear boundary is mysterious to us.
POSSESSION
The temporary possession of a person's body, or some member of that body, by an alien will, as exemplified in automatic writing and obsession.
It would doubtless amaze the scientifically orthodox to know how many people habitually and successfully practice the dubious art of automatic writing—not mediums, so-called, but people of refinement and intelligence. Although the messages received in this way may emanate from the subconscious mind of the performer, there is evidence to indicate that they come sometimes from an intelligence discarnate, or from a person remote from the recipient in space.
If such is indeed the case, if the will is extraneous, how does it possess itself of the nerves and muscles of the hand of the writer? The Higher Space Hypothesis is of assistance here. It is only necessary to remember that from the fourth dimension the interior of a solid is as much exposed as the interior of a plane figure is exposed from the region of the third dimension. A four-dimensional being would experience no difficulty, under suitable conditions, in possessing itself of any part of the bodily mechanism of another.
The same would hold true in cases of possession and obsession; for if the bastion of the hand can thus be captured, so also may the citadel of the brain. Certain familiar forms of hypnotism are not different from obsession, the hypnotizer using the brain and body of his subject as though they were his own. All unconsciously to himself, he has called into play four-dimensional mechanics. Many cases of so-called dual personality are more easily explicable as possession by an alien will than on the less credible hypothesis that the character, habits, and language of a person can change utterly in a moment of time.