Our blue patch of color grows larger and larger; it ceases to be blue and faint; at the last it has been replaced by an expanse of vivid green, and we see the tree just before us.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?
20.