, must be able to perceive at one and the
same instant more of a panorama than we can. I find that a few
persons can, by what they often describe as a kind of touch-sight,
visualise at the same moment all round the image of a solid body.
Many can do so nearly, but not altogether round that of a
terrestrial globe. An eminent mineralogist assures me that he is
able to imagine simultaneously all the sides of a crystal with which
he is familiar. I may be allowed to quote a curious faculty of my
own in respect to this. It is exercised only occasionally and in
dreams, or rather in nightmares, but under those circumstances I am
perfectly conscious of embracing an entire sphere in a single
perception. It appears to lie within my mental eyeball, and to be
viewed centripetally.

This power of comprehension is practically attained in many cases by
indirect methods. It is a common feat to take in the whole
surroundings of an imagined room with such a rapid mental sweep as
to leave some doubt whether it has not been viewed simultaneously.
Some persons have the habit of viewing objects as though they were
partly transparent; thus, if they so dispose a globe in their
imagination as to see both its north and south poles at the same time,
they will not be able to see its equatorial parts. They can also
perceive all the rooms of an imaginary house by a single mental
glance, the walls and floors being as if made of glass. A fourth
class of persons have the habit of recalling scenes, not from the
point of view whence they were observed, but from a distance, and
they visualise their own selves as actors on the mental stage. By
one or other of these ways, the power of seeing the whole of an
object, and not merely one aspect of it, is possessed by many persons.

The place where the image appears to lie, differs much. Most persons
see it in an indefinable sort of way, others see it in front of the
eye, others at a distance corresponding to reality. There exists a
power which is rare naturally, but can, I believe, be acquired
without much difficulty, of projecting a mental picture upon a piece
of paper, and of holding it fast there, so that it can be outlined
with a pencil. To this I shall recur.

Images usually do not become stronger by dwelling on them; the first
idea is commonly the most vigorous, but this is not always the case.
Sometimes the mental view of a locality is inseparably connected
with the sense of its position as regards th