find such. Bat what I mean is this: the idea of space (as also of time or duration) is an abstract or partial idea; an idea of a certain quality or relation, which we evidently see to be necessarily existing; and yet which (not being itself a substance) at the same time necessarily presupposes a substance, without which it could not exist; which substance consequently must be itself (much more, if possible) necessarily existing. I know not how to explain this so well as by the following similitude: a blind man, when he tries to frame to himself the idea of body, his idea is nothing but that of hardness. A man that had eyes, but no power of motion, or sense of feeling at all, when he tried to frame to himself the idea of body, his idea would be nothing but that of colour. Now as, in these cases, hardness is not body; and colour is not body; but yet, to the understanding of these persons, those properties necessarily infer the being of a substance, of which substance itself the persons have no idea: so space, to us, is not itself substance, but it necessarily infers the being of a substance, which affects none of our present senses; and being itself necessary, it follows that the substance, which it infers, is (much more) necessary.
I am, Sir.
Your affectionate Friend and Servant.
January 29, 1714.
THE FIFTH LETTER,
Reverend Sir,—You have very comprehensively expressed, in six or seven lines, all the difficulties of my letter, which I should have endeavoured to have made shorter, had I not been afraid an improper impression might possibly occasion a mistake of my meaning. I am very glad the debate is come into so narrow a compass; for I think now it entirely turns upon this, whether our ideas of Space and duration are partial, so as to presuppose the existence of some other thing. Your similitude of the blind man is very apt to explain your meaning, (which I think I fully understand,)
