For that would be to run in a circle, and make one idea depend on another, while at the same time the latter depends on the former.

Our modern philosophy, therefore, leaves us no just nor satisfactory idea of solidity; nor consequently of matter.
This argument will appear entirely conclusive to every one that comprehends it; but because it may seem abstruse and intricate to the generality of readers, I hope to be excused, if I endeavour to render it more obvious by some variation of the expression.

In order to form an idea of solidity, we must conceive two bodies pressing on each other without any penetration; and it is impossible to arrive at this idea, when we confine ourselves to one object, much more without conceiving any.

Two non-entities cannot exclude each other from their places; because they never possess any place, nor can be endowed with any quality.

Now I ask, what idea do we form of these bodies or objects, to which we suppose solidity to belong?
To say, that we conceive them merely as solid, is to run on in infinitum.