r 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.

CLAIRVOYANCE IN SPACE

_Vision at a distance and the exercise of a superior power of sight_.

Clairvoyance in space is of various kinds and degrees. Sometimes it
consists in the perception of super-physical phenomena--the
unfurling of a strange and wonderful land; and again it appears to
be a higher power of ordinary vision, a kind of seeing to which the
opacity of solids offers no impediment, or one involving spatial
distances too great and too impeded for normal physical vision to be
effective.

That clairvoyance which consists in the ability to perceive not
alone the superficies of things as ordinary vision perceives them,
but their interiors as well, is analogous to the power given by the
X-ray, by means of which, on a fluorescent screen, a man may behold
the beating of his own heart. But, if the reports of trained
clairvoyants are to be believed, there is this difference:
everything appears to them without the distortions due to perspective,
objects being seen as though they were inside and not outside of the
perceiving organ, or as though the observer were in the object
perceived; or in all places at the same time.

Our analogy makes all this intelligible. To the flat-man,
clairvoyance in space would consist in that power of perception
which we exercise in reference to his plane. From the third
dimension the boundaries of plane figures offer no impediment
to the view of their interiors, and they themselves in no way
impede our vision of surrounding objects. If we assume that
clairvoyanc