CALL
SOLIDITY. I will not dispute whether this acceptation of the word solid
be nearer to its original signification than that which mathematicians
use it in. It suffices that I think the common notion of solidity will
allow, if not justify, this use of it; but if any one think it better to
call it IMPENETRABILITY, he has my consent. Only I have thought the term
solidity the more proper to express this idea, not only because of its
vulgar use in that sense, but also because it carries something more of
positive in it than impenetrability; which is negative, and is perhaps
more a consequence of solidity, than solidity itself. This, of all
other, seems the idea most intimately connected with, and essential to
body; so as nowhere else to be found or imagined, but only in matter.
And though our senses take no notice of it, but in masses of matter, of
a bulk sufficient to cause a sensation in us: yet the mind, having once
got this idea from such grosser sensible bodies, traces it further, and
considers it, as well as figure, in the minutest particle of matter
that can exist; and finds it inseparably inherent in body, wherever or
however modified.

2. Solidity fills Space.

This is the idea which belongs to body, whereby we conceive it to fill
space. The idea of which filling of space is,--that where we imagine any
space taken up by a solid substance, we conceive it so to possess it,
that it excludes all other solid substances; and will for ever hinder
any other two bodies, that move towards one another in a straight line,
from coming to touch one another, unless it removes from between them
in a line not parallel to that which they move in. This idea of it,
the bodies which we ordinarily handle sufficiently furnish us with.

3. Distinct from Space.

This resistance, whereby it keeps other bodies out of the space which it
possesses, is so great, that no force, how great soever, can surmount
it. All the bodies in the world, pressing a drop of water on all sides,
will never be able to overcome the resistance which it will make, soft
as it is, to their approaching one another, till it be removed out of
their way: whereby our idea of solidity is distinguished both from pure
space, which is capable neither of resistance nor motion; and from
the ordinary idea of hardness. For a man may conceive two bodies at
a distance, so as they may approach one another, without touching
or displacing any solid thing, till their superfic