Physics   

belief: it is not only the boundaries of the vessel which seem to be
place, but also what is between them, regarded as empty. Just, in
fact, as the vessel is transportable place, so place is a non-portable
vessel. So when what is within a thing which is moved, is moved and
changes its place, as a boat on a river, what contains plays the part
of a vessel rather than that of place. Place on the other hand is
rather what is motionless: so it is rather the whole river that is
place, because as a whole it is motionless.
Hence we conclude that the innermost motionless boundary of what
contains is place.
This explains why the middle of the heaven and the surface which faces
us of the rotating system are held to be 'up' and 'down' in the strict
and fullest sense for all men: for the one is always at rest, while
the inner side of the rotating body remains always coincident with
itself. Hence since the light is what is naturally carried up, and the
heavy what is carried down, the boundary which contains in the
direction of the middle of the universe, and the middle itself, are
down, and that which contains in the direction of the outermost part
of the universe, and the outermost part itself, are up.
For this reason, too, place is thought to be a kind of surface, and as
it were a vessel, i.e. a container of the thing.
Further, place is coincident with the thing, for boundaries are
coincident with the bounded.
Part 5
If then a body has another body outside it and containing it, it is in
place, and if not, not. That is why, even if there were to be water
which had not a container, the parts of it, on the one hand, will be
moved (for one part is contained in another), while, on the other
hand, the whole will be moved in one sense, but not in another. For as
a whole it does not simultaneously change its place, though it will be
moved in a circle: for this place is the place of its parts. (Some
things are moved, not up and down, but in a circle; others up and
down, such things namely as admit of condensation and rarefaction.)
As was explained, some things are potentially in place, others
actually. So, when you have a homogeneous substance which is
continuous, the parts are potentially in place: when the parts are
separated, but in contact, like a heap, they are actually in place.
Again, (1) some things are per se in place, namely every body which is
movable either by way of locomotion or by way of increase is per se
somewhere, but the heaven, as has been said, is not anywhere as a
whole, nor in any place, if at least, as we must suppose, no body
contains it. On the line on which it is moved, its parts have place:
for each is contiguous the next.
But (2) other things are in place indirectly, through something
conjoined with them, as the soul and the heaven. The latter is, in a
way, in place, for all its parts are: for on the orb one part contains
another. That is why the upper part is moved in a circle, while the
All is not anywhere. For what is somewhere is itself something, and
there must be alongside it some other thing wherein it is and which
contains it. But alongside the All or the Whole there is nothing
outside the All, and for this reason all things are in the heaven; for
the heaven, we may say, is the All. Yet their place is not the same as
the heaven. It is part of it, the innermost part of it, which is in
contact with the movable body; and for this reason the earth is in
water, and this in the air, and the air in the aether, and the aether
in heaven, but we cannot go on and say that the heaven is in anything
else.
It is clear, too, from these considerations that all the problems
which were raised about place will be solved when it is explained in
this way:
(1) There is no necessity that the place should grow with the body in
it,
(2) Nor that a point should have a place,
(3) Nor that two bodies should be in the same place,