In the Absolute these, of course, possess a unity, we

must conclude that the unity is not material. In coming

together their extensional character is transmuted.

There are a variety of spatial systems, independent of

each other, and each changed beyond itself, when

absorbed in the one non-spatial system. Thus, with

regard to their unity, Space and Time have similar

characters (pp. 210-214).

That which for ordinary purposes I call "real"

Nature, is the extended world so far as related to my

body. What forms a spatial system with that body has

"real" extension. But even "my body" is ambiguous, for

the body, which I imagine, may have no spatial relation

to the body which I perceive. And perception too can be

illusive, for my own body in dreams is not the same

thing with my true "real" body, nor does it enter with

it into any one spatial arrangement. And what in the end

I mean by my "real" body, seems to be this. I make a

spatial construction from my body, as it comes to me

when awake. This and the extended which will form a

single system of spatial relations together with this, I

consider as real. And whatever extension falls outside of this

one system of interrelation, I set down as

"imaginary." And, as a mere subordinate point of view,

this may do very well. But it is quite another thing on

such a ground to deny existence in the Absolute to every

other spatial system. For we have the "imaginary"

extension on our hands as a fact which remains, and

which should cause us to hesitate. And, when we reflect,

we see clearly that a variety of physical arrangements

may exist without anything like spatial interrelation.

They will have their unity in the Whole, but no

connections in space each outside its own proper system

of matter. And Nature therefore cannot properly be

called a single world, in the sense of possessing a

spatial unity.

Thus we might have any number of physical systems,

standing independent of spatial relations with each

other. And we may go on from this to consider another

point of interest. Such diverse worlds of matter might

to any extent still act on and influence one another.

But, to speak strictly, they could not interpenetrate at

any point. Their interaction, however intimate, could

not be called penetration; though, in itself and in its

effects, it might involve a closer unity. Their spaces

always would remain apart, and spatial contact would be

impossible. But inside each world the case, as to

penetration, might be different. The penetration of one

thing by another might there even be usual; and I will

try to show briefly that this presents no difficulty.

The idea of a Nature made up of solid matter,

interspaced with an absolute void, has been inherited, I

presume, from Greek metaphysics. And, I think, for the

most part we hardly realize how entirely this view lies

at the mercy of criticism. I am speaking, not of physics

and the principles employed by physics, but of what may

be called the metaphysics of the literary market-place.

And the notion common there, that one extended

thing cannot penetrate another, rests mainly on

prejudice. For whether matter, conceivably and possibly,

can enter into matter or not, depends entirely on the

sense in which matter is taken. Penetration means the

abolition of spatial distinction, and we may hence

define matter in such a way that, with loss of spatial

distinction, itself would be abolished. If, that is to

say, pieces of matter are so one thing with their

extensions as, apart from these, to keep no individual

difference--then these pieces obviously cannot

penetrate; but, otherwise, they may. This seems to me

clear, and I will go on to explain it shortly.