origin. We know the process of digestion and assimilation, and the laws which
govern them, although we do not understand the ultimate nature and origin of
life which makes these possible.
The Qualities of Objects Exist in the Mind.—Yet even in the relatively simple
description which we have proposed many puzzles confront us, and one of them
appears at the very outset. This is that the qualities which we usually ascribe to
objects really exist in our own minds and not in the objects at all. Take, for
instance, the common qualities of light and color. The physicist tells us that what
we see as light is occasioned by an incredibly rapid beating of ether waves on
the retina of the eye. All space is filled with this ether; and when it is light—that
is, when some object like the sun or other light-giving body is present—the ether
is set in motion by the vibrating molecules of the body which is the source of
light, its waves strike the retina, a current is produced and carried to the brain,
and we see light. This means, then, that space, the medium in which we see
objects, is not filled with light (the sensation), but with very rapid waves of
ether, and that the light which we see really occurs in our own minds as the
mental response to the physical stimulus of ether waves. Likewise with color.
Color is produced by ether waves of different lengths and degrees of rapidity.
Thus ether waves at the rate of 450 billions a second give us the sensation of red;
of 472 billions a second, orange; of 526 billions a second, yellow; of 589 billions
a second, green; of 640 billions a second, blue; of 722 billions a second, indigo;
of 790 billions a second, violet. What exists outside of us, then, is these ether
waves of different rates, and not the colors (as sensations) themselves. The
beautiful yellow and crimson of a sunset, the variegated colors of a landscape,
the delicate pink in the cheek of a child, the blush of a rose, the shimmering
green of the lake—these reside not in the objects themselves, but in the
consciousness of the one who sees them. The objects possess but the quality of
reflecting back to the eye ether waves of the particular rate corresponding to the
color which we ascribe to them. Thus "red" objects, and no others, reflect back
ether waves of a rate of 450 billions a second: "white" objects reflect all rates;
"black" objects reflect none.
The case is no different with regard to sound. When we speak of a sound coming
from a bell, what we really mean is that the vibrations of the bell have set up
waves in the air between it and our ear, which have produced corresponding
vibrations in the ear; that a nerve current was thereby produced; and that a sound
was heard. But the sound (i.e., sensation) is a mental thing, and exists only in our
own consciousness. What passed between the sounding object and ourselves was