world
as it really is,
not only in the philosophical sense of this expression, but
even in
the most ordinary
geometrical
sense. We have never seen a
cube,
a
sphere,
etc., we have always seen only surfaces. Realizing this, we mentally
correct what we see. Behind the surfaces we
think
the solid. But we can never
represent
a solid to ourselves; we cannot represent
a cube or a sphere not in
perspective, but from all sides at once.
It is clear that the world does not exist in perspective; yet we are unable to
see it in any other way. We see everything only in perspective, i.e. in
perceiving it, we distort the world with our eye. And we know that we distort
it. We know that it is not as we see it.
And mentally we continually
correct
what the eye sees,
substituting
the real content for those symbols of things
which our sight shows us.
Our sight is a complex faculty. It consists of visual sensations,
plus
the
memory of sensations of touch. A child tries to touch everything he sees - the
nose of his nurse, the moon, the dancing spot of reflected sunlight on the
wall. He learns only gradually to distinguish between the near and the far
by
sight alone.
But we know that even in mature years we are easily subject to
optical illusions.
We see
distant objects as flat, i.e. even more incorrectly, for relief is, after
all, a symbol indicating a certain property of objects. At a great distance a
man is outlined for us in silhouette. This happens because at long range we
can never touch anything, and our eye has not been trained to notice the
differences in surfaces which, at close range, are felt by the fingertips.*
We are never able to see even a small bit of the external
world as it is, i.e.
such as we know it to be.
We can never see a writing desk or a cupboard
simultaneously from all sides, as well as inside.
Our eye distorts the external
world in a certain way to enable us, in looking about, to determine the
position of objects relatively to ourselves. But
*
In this connection, observations made on the blind beginning to see are very
interesting.
The periodical
Slepetz
('The Blind Man') 1912, contains a description, based on
direct observation, of how men, blind
from birth,
learn to see after an operation
which
has restored their sight.
This is how a youth of seventeen describes his experiences after the restoration of his
sight by the removal of a cataract. On the third day after the operation he was asked
what he saw; he replied that he saw a vast expanse of light with dim objects moving in
it. He did not distinguish these objects. Only after four days did he begin to distinguish
them, and
only after two weeks, when his eyes became used to the light, did he begin to
make a practical use of his sight for the discernment of objects. He was shown all the
colours of the spectrum and very quickly mastered them, except the yellow and the
green which he kept on confusing for a long time. A cube, a sphere and
a pyramid,
placed before him, seemed to him a square, a flat disc and a triangle. When a flat disc
was placed next