ternal existences, there remains nothing, which can afford us a just
and constituent idea of body.

Add to this, that, properly speaking, solidity or impenetrability is
nothing, but an impossibility of annihilation, as [Part II. Sect. 4.]
has been already observed: For which reason it is the more necessary
for us to form some distinct idea of that object, whose annihilation we
suppose impossible. An impossibility of being annihilated cannot exist,
and can never be conceived to exist, by itself: but necessarily
requires some object or real existence, to which it may belong. Now
the difficulty still remains, how to form an idea of this object
or existence, without having recourse to the secondary and sensible
qualities.

Nor must we omit on this occasion our accustomed method of examining
ideas by considering those impressions, from which they are derived. The
impressions, which enter by the sight and hearing, the smell and taste,
are affirmed by modern philosophy to be without any resembling objects;
and consequently the idea of solidity, which is supposed to be real, can
never be derived from any of these senses. There remains, therefore,
the feeling as the only sense, that can convey the impression, which is
original to the idea of solidity; and indeed we naturally imagine, that
we feel the solidity of bodies, and need but touch any object in order
to perceive this quality. But this method of thinking is more popular
than philosophical; as will appear from the following reflections.

First, It is easy to observe, that though bodies are felt by means of
their solidity, yet the feeling is a quite different thing from the
solidity; and that they have not the least resemblance to each other.
A man, who has the palsey in one hand, has as perfect an idea of
impenetrability, when he observes that hand to be supported by the
table, as when he feels the same table with the other hand. An object,
that presses upon any of our members, meets with resistance; and that
resistance, by the motion it gives to the nerves and animal spirits,
conveys a certain sensation to the mind; but it does not follow, that
the sensation, motion, and resistance are any ways resembling.

Secondly, The impressions of touch are simple impressions, except when
considered with regard to their extension; which makes nothing to the
present purpose: And from this simplicity I infer, that they neither
represent solidity, nor any real object. For let us put