BOOK I PART IV
a circle. Extension must necessarily be consid-
ered either as coloured, which is a false idea;
I or as solid, which brings us back to the first
question. We may make the same observation
concerning mobility and figure; and upon the
whole must conclude, that after the exclusion
of colours, sounds, heat and cold from the rank
of external 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 impossi-
bility of annihilation, as (Part II. Sect. 4.) has
been already observed: For which reason it is
the more necessary for us to form some dis-
tinct idea of that object, whose annihilation we
suppose impossible. An impossibility of be-
ing annihilated cannot exist, and can never be