6. What solidity is.
If any one ask me, What this solidity is, I send him to his senses to inform him. Let him put a
flint or a football between his hands, and then endeavour to join them, and he will know. If he thinks this not a
sufficient explication of solidity, what it is, and wherein it consists; I promise to tell him what it is, and wherein it
consists, when he tells me what thinking is, or wherein it consists; or explains to me what extension or motion is,
which perhaps seems much easier. The simple ideas we have, are such as experience teaches them us; but if,
beyond that, we endeavour by words to make them clearer in the mind, we shall succeed no better than if we went
about to clear up the darkness of a blind man's mind by talking; and to discourse into him the ideas of light and
colours. The reason of this I shall show in another place.
