d for me in experiences of some sort, or I would never know
anything as near to or far from my body.

Thus, all our sensory experiences are experiences that fall into a
certain system or order. It is a system which we all recognize
implicitly, for we all reject as merely imaginary those experiences
which lack this setting. If my eyes are shut--I am speaking now of the
eyes as experienced, as felt or perceived, as given in sensation--I
never say; "I see my desk," no matter how vivid the image of the
object. Those who believe in "second sight" sometimes talk of seeing
things not in this setting, but the very name they give to the supposed
experience indicates that there is something abnormal about it. No one
thinks it remarkable that I see the desk before which I perceive myself
to be sitting with open eyes. Every one would think it strange if I
could see and describe the table in the next room, now shut away from
me. When a man thinks he hears his name pronounced, and, turning his
head, seeks in vain for the speaker, he sets his experience down as a
hallucination. He says, I did not really hear that; I merely imagined
it.

May one not, with open eyes, have a hallucination of vision, just as
one may seem to hear one's name pronounced when no one is by?
Certainly. But in each case the experience may be proved to be a
hallucination, nevertheless. It may be recognized that the sensory
setting is incomplete, though it may not, at first, seem so. Thus the
unreal object which seems to be seen may be found to be a thing that
cannot be touched. Or, when one has attained to a relatively complete
knowledge of the system of experiences recognized as sensory, one may
make use of roundabout methods of ascertaining that the experience in
question does not really have the right setting. Thus, the ghost which
is seen by the terrified peasant at midnight, but which cannot be
photographed, we may unhesitatingly set down as something imagined and
not really seen.

All our sensations are, therefore, experiences which take their place
in a certain setting. This is our ultimate criterion. We need not
take the word of the philosopher for it. We need only reflect, and ask
ourselves how we know that, in a given case, we are seeing or hearing
or touching something, and are not merely imagining it. In every case,
we shall find that we come back to the same test. In common life, we
apply the test instinctively, and with little re