240 Public Lectures
“Much the greater part of the volume that seems to be filled
. . . is really unoccupied.”1 What you really hold in the
palm of your hand is a universe of particles in rapid vibra-
tory motion. At this point, therefore, commonsense is in-
vited to extend the concept of apparent-but-not-real qualifi-
cation to the white of the marble itself, and for seemingly the
same reasons as in the case of the rapidly oscillating marble.
I say “seemingly” the same reasons. The reasons are not all
really the same. In the first case, we pointed to the existence
of a white marble in motion to explain the appearance of
white throughout a region of space larger than the marble
itself, and we believed that the apparent white was never
more than six inches away from the real white. In the second
case, however, we can no longer speak of white particles
moving rapidly to produce the appearance of a continuous
white patch. The ultimate particles of matter are colorless,
such that it would be false to say that a blade of grass is
green because its atoms are green. So now we discover that
the perceived white is not even in the general region of the
marble at all, be it in motion or at rest. Locke would love this
conclusion, which contains by implication the denial that
white exists anywhere in the physical world, and which re-
veals sharply the problem of perception. If qualities may
appear in normal circumstances to inhere in material bodies
without, as we have seen, really doing so, how are we to dis-
tinguish the real properties from the unreal, and where are
we to locate such as have no physical existence? The answer
to this question can be developed best by turning now to
Locke’s own views on matter, mind, and the relation between
them. We shall take material existence first.
Our illustration of the oscillating particle has indicated
the content of what Locke called the “corpuscularian”2 hy-
1ABC of Atoms, p. 8. 2 ɪv, 3, 16.