stuck into water looks
bent, but feels straight to the touch; why believe the testimony of one
sense rather than that of another?

Such questionings led to far-reaching consequences. They resulted in a
forlorn distrust of the testimony of the senses, and to a doubt as to
our ability to know anything as it really is.

Now, the distinction between appearances and realities exists for us as
well as for the ancient skeptic, and without being tempted to make such
extravagant statements as that there is no such thing as truth, and
that every appearance is as real as any other, we may admit that it is
not very easy to see the full significance of the distinction, although
we are referring to it constantly.

For example, we look from our window and see, as we say, a tree at a
distance. What we are conscious of is a small bluish patch of color.
Now, a small bluish patch of color is not, strictly speaking, a tree;
but for us it represents the tree. Suppose that we walk toward the
tree. Do we continue to see what we saw before? Of course, we say
that we continue to see the same tree; but it is plain that what we
immediately perceive, what is given in consciousness, does not remain
the same as we move. Our blue patch of color grows larger and larger;
it ceases to be blue and faint; at the last it has been replaced by an
expanse of vivid green, and we see the tree just before us.

During our whole walk we have been seeing the tree. This appears to
mean that we have been having a whole series of visual experiences, no
two of which were just alike, and each of which was taken as a
representative of the tree. Which of these representatives is most
like the tree? Is the tree _really_ a faint blue, or is it _really_ a
vivid green? Or is it of some intermediate color?

Probably most persons will be inclined to maintain that the tree only
seems blue at a distance, but that it really is green, as it appears
when one is close to it. In a sense, the statement is just; yet some
of those who make it would be puzzled to tell by what right they pick
out of the whole series of experiences, each of which represents the
tree as seen from some particular position, one individual experience,
which they claim not only represents the tree as seen from a given
point but also represents it as it is. Does this particular experience
bear some peculiar earmark which tells us that it is like the real tree
while the others are unlike it?

2