The Cartesians will except against me as speaking of space without body...

The Cartesians will except against me as speaking of space without body, which they make to be the same thing; to whom let me say, that if spacium be corpus, and corpus spacium, then it is as true too that extensio is corpus, and corpus extensio, which is a pretty harsh kind of expression and that which is so distant from truth, that I do not remember that I have anywhere met with it from them; and yet I would fain know any other difference between extensio and spacium than that which I have above mentioned.

If they will say omne extensum et omnis res positiva extensa corpus, et vice versâ, I fully consent. But then it is only to say that body is the only being capable of distance between its own parts, which is extension (for I do not know why angels may not be capable of the relation of distance, in respect of one another), which shows plainly the difference of the words extension, which is for distance, a part of the same body, or that which is considered but as one body, and that of space, which is the distance between any two beings, without the consideration of body interjacent.

Besides this, there seems to me this great and essential difference between space and body, that body is divisible into separable parts, but space is not.

This, I think, is so plain that it needs no proof; for if one take a piece of matter, of an inch square, for example, and divide it into two, the parts will be separated if set at further distance one from another; but yet nobody, I think, amongst those who are most for the reality of space, say the parts of space are or can be removed to a further distance one from another.

And he that, imagining the idea of a space of an inch square, can tell how to separate the parts of it, and remove them one from another, has, I confess, a much more powerful fancy than I. It is no more strange, therefore, that extension, which is the relation of distance between parts of the same being, should be proper only to body, which alone has parts, than that the relation of filiation should be proper only to men.