242 Public Lectures
the bottom of which will probably never be probed by the
human mind.1
Bodies, which are aggregates of cohering atoms, possess
all the properties exhibited by atoms save one. They have
shape and size, they move and are numerable, but they are
not solid in the same absolute sense that atoms are, since they
are for the most part compressible. These properties of
“physical substances” are called “primary,” and are such
that no matter what alteration the body undergoes, it pos-
sesses them in some form or other as long as it is body at all.
Likewise, bodies have the passive power to be causally af-
fected by other bodies, by the collision of parts.
Now that we have described bodily existence, let us indi-
cate in a word the nature of the space which is the possibility
of bodily motion. Though Locke held successively three
fairly distinct views of space,2 in the end he completely aban-
doned the first two and adhered to the theory of absolute
space, as it was propounded in his day by the Cambridge Pla-
tonist More and by Newton. This is the view he expressed
in the Essay. As there described, space is “uniform and
boundless,” itself unmoved and unalterable by the motion of
bodies in it. The material universe in space has limits, but
space itself has none. Take the extreme opposite of solidity,
which is the characteristic of body, and you have a character-
istic of space.
Now it was necessary to present for our comprehension
Locke’s conception of this great spatial receptacle, together
with his conception of the bodies it contains. We must under-
stand clearly the atomic and spatial constitution of our
1 ii, 23, 24, passim. See also Elements of Natural Philosophy. Wks. Vol.
Ill, p. 281.
2 J. Gibson, op. cit. pp. 248-250.