re
almost endless instances; the stick bent in water; the whistle changing
pitch with change of distance from the ear; objects doubled when the eye
is pushed; the destroyed star still visible, etc., etc. For our
consideration we may take the case of a spherical object that presents
itself to one observer as a flat circle, to another as a somewhat
distorted elliptical surface. This situation gives empirical proof, so
it is argued, of the difference between a real object and mere
appearance. Since there is but one object, the existence of two
_subjects_ is the sole differentiating factor. Hence the two
appearances of the one real object is proof of the intervening
distorting action of the subject. And many of the Neo-realists who deny
the difference in question, admit the case to be one of knowledge and
accordingly to constitute an epistemological problem. They have in
consequence developed wonderfully elaborate schemes of sundry kinds to
maintain "epistemological monism" intact.

Let us try to keep close to empirical facts. In the first place the two
unlike appearances of the one sphere are physically necessary because of
the laws of reaction of light. If the one sphere did _not_ assume these
two appearances under given conditions, we should be confronted with a
hopelessly irreconcilable discrepancy in the behavior of natural energy.
That the result is natural is evidenced by the fact that two cameras--or
other arrangements of apparatus for reflecting light--yield precisely
the same results. Photographs are as genuinely physical existences as
the original sphere; and they exhibit the two geometrical forms.

The statement of these facts makes no impression upon the confirmed
epistemologist; he merely retorts that as long as it is admitted that
the organism is the cause of a sphere being seen, from different points,
as a circular and as an elliptical surface, the essence of his
contention--the modification of the real object by the subject--is
admitted. To the question why the same logic does not apply to
photographic records he makes, as far as I know, no reply at all.

The source of the difficulty is not hard to see. The objection assumes
that the alleged modifications of _the_ real object are cases of
_knowing_ and hence attributable to the influence of a _knower_.
Statements which set forth the doctrine will always be found to refer to
the organic factor, to the eye, as an observer or a percipient. Even
when referen