r hand, wave it up and down past the side of your hand which is
turned from the light, the paper being of course farther from the
window. You will see, as it passes, a strong gleam of light strike on
your hand, and light it considerably on its dark side. This light is
_reflected_ light. It is thrown back from the paper (on which it strikes
first in coming from the window) to the surface of your hand, just as a
ball would be if somebody threw it through the window at the wall and
you caught it at the rebound.

Next, instead of the note-paper, take a red book, or a piece of scarlet
cloth. You will see that the gleam of light falling on your hand, as
you wave the book, is now reddened. Take a blue book, and you will find
the gleam is blue. Thus every object will cast some of its own color
back in the light that it reflects.

54. Now it is not only these books or papers that reflect light to your
hand: every object in the room on that side of it reflects some, but
more feebly, and the colors mixing all together form a neutral[11]
light, which lets the color of your hand itself be more distinctly seen
than that of any object which reflects light to it; but if there were no
reflected light, that side of your hand would look as black as a coal.

55. Objects are seen therefore, in general, partly by direct light, and
partly by light reflected from the objects around them, or from the
atmosphere and clouds. The color of their light sides depends much on
that of the direct light, and that of the dark sides on the colors of
the objects near them. It is therefore impossible to say beforehand what
color an object will have at any point of its surface, that color
depending partly on its own tint, and partly on infinite combinations of
rays reflected from other things. The only certain fact about dark sides
is, that their color will be changeful, and that a picture which gives
them merely darker shades of the color of the light sides must assuredly
be bad.

56. Now, lay your hand flat on the white paper you are drawing on. You
will see one side of each finger lighted, one side dark, and the shadow
of your hand on the paper. Here, therefore, are the three divisions of
shade seen at once. And although the paper is white, and your hand of a
rosy color somewhat darker than white, yet you will see that the shadow
all along, just under the finger which casts it, is darker than the
flesh, and is of a very deep gray. The reason of this is,