_Hamlet._ My father,--methinks, I see my father.
_Horatio._ O, where, my lord?
_Hamlet._ In my mind's eye, Horatio.
I
It is a commonplace taught from nursery to university that we see
with our eyes, hear with our ears, and feel with our fingers. This is
the truth, but not the whole truth. Indispensable as are the sense
organs in gaining an acquaintance with the world in which we live,
yet they alone do not determine how extensive or how accurate that
acquaintance shall be. There is a mind behind the eye and the ear and
the finger-tips which guides them in gathering information, and gives
value and order to the exercise of the senses. This is particularly
true of vision,--the most intellectual of all the senses, the one in
which mere acuteness of the sense organ counts least and the training
in observation counts most. The eagle's eye sees farther, but our
eyes tell us vastly more of what is seen.
The eye may be compared to a photographic camera, with its eyelid
cap, its iris shutter, its lens, and its sensitive plate,--the
retina; when properly adjusted for distance and light, the image
is formed on the retina as on the glass plate, and the picture is
taken. So far the comparison is helpful; but while the camera takes a
picture whenever and wherever the plate happens to be exposed, the
complete act of seeing requires some coöperation on the part of the
mind. The retina may be exposed a thousand times and take but few
pictures; or perhaps it is better to say that the pictures may be
taken, but remain undeveloped and evanescent. The pictures that are
developed are stacked up, like the negatives in the photographer's
shop, in the pigeon-holes of our mental storerooms,--some faded and
blurred, some poorly arranged or mislaid, some often referred to and
fresh prints made therefrom, and some quite neglected.
In order to see, it is at once necessary that the retina be suitably
exposed toward the object to be seen, and that the mind be favorably
disposed to the assimilation of the impression. True seeing,
observing, is a double process, partly objective or outward--the
thing seen and the retina,--and partly subjective or inward--the
picture mysteriously transferred to the mind's representative,
the brain, and there received and affiliated with other images.
Illustrations of such seeing with the "mind's eye" are not far to
seek. Wherever the beauties and conformations of natural scenery
invite the eye of man, does he discover familiar forms and faces;
the forces of nature have rough-hewn the rocks, but the human eye
detects and often creates the resemblances. The stranger to whom such
curiosities of form are first pointed out often finds it difficult to
discover the resemblance, but once seen, the face or form obtrudes
itself in every view, and seems the most conspicuous feature in
the outlook. The flickering fire furnishes a fine background for
the activity of the mind's eye, and against this it projects the
forms and fancies which the leaping flames and the burning embers
from time to time suggest. Not all see these fire-pictures readily,
for our mental eyes differ more from one another than the physical
ones, and perhaps no two persons see the same picture in quite the
same way. It is not quite true, however, as many have held, that in
waking hours we all have a world in common, but in dreams each has
a world of his own; for our waking worlds are made different by the
differences in what engages our interest and our attention. It is
true that our eyes when open are opened very largely to the same
views, but by no one observer are all these views, though visible,
really seen.
This characteristic of vision often serves as a source of amusement.
The puzzle picture with its tantalizing face, or animal, or what
not, hidden in the trees, or fantastically constructed out of
heterogeneous elements that make up the composition, is to many quite
irresistible. We turn it about in all directions, wondering where
the hidden form can be, scanning every detail of the picture, until
suddenly a chance glimpse reveals it, plainly staring us in the face.
When several persons are engaged in this occupation, it is amusing to
observe how blind each is to what the others see; their physical eyes
see alike, but their mental eyes reflect their own individualities.
Of the many thousands of persons who handle our silver dollar,
but few happen to observe the lion's head which lies concealed in
the representation of the familiar head of Liberty; frequently
even a careful examination fails to detect this hidden emblem of
British rule; but, as before, when once found, it is quite obvious
(Fig. 1).[10] For similar reasons it is a great aid in looking
for an object to know what to look for; to be readily found, the
object, though lost to sight, should be to memory clear. Searching
is a mental process similar to the matching of a piece of fabric
in texture or color, when one has forgotten the sample and must
rely upon the remembrance of its appearance. If the recollection
is clear and distinct, recognition takes place when the judgment
decides that what the physical eye sees corresponds to the image
in the mind's eye; with an indistinct mental image the recognition
becomes doubtful or faulty. The novice in the use of the microscope
experiences considerable difficulty in observing the appearance which
his instructor sees and describes, and this because his conception
of the object to be seen is lacking in precision. Hence his training
in the use of the microscope is distinctly aided by consulting the
illustrations in the textbook, for they enable his mental eye to
realize the pictures which it should entertain. He may be altogether
too much influenced by the pictures thus suggested to his mental
vision, and draw what is really not under his microscope at all; much
as the young arithmetician will manage to obtain the answer which the
book requires even at the cost of a resort to very unmathematical
processes. For training in correct and accurate vision it is
necessary to acquire an alert mental eye, that observes all that is
objectively visible, but does not permit the subjective to add to or
modify what is really present.