Rarity [Decompression] and Density [Compression]

There are some who think that the existence of compression [density] and decompression [rarity] shows that there is a void.

Xuthus says if decompression and compression do not exist then things cannot contract and be compressed.

Then either:

• there would be no movement at all or
• the universe would bulge, or
• air and water must always change into equal amounts or
  • e.g. if air were made out of a cupful of water, a cupful of water would be made out of a cupful of air, or
• void must necessarily exist

This is because compression and expansion cannot take place without compression and decompression.

If “decompressed” means that its many voids exist separately, then this is impossible because void cannot exist separately.

But if “decompressed” means that there is void in it, then this is possible.

This means that:

1. The void is not a condition of all movement. It is only a condition of upwards movement.

This is because decompression implies something lightweight. This is why fire is decompressed.

2. The void turns out to be a condition not of actual movement, but that the void carries things up.

Yet how can void have a local movement or a place?

If a void moves into something, then that something is void of the void before that void has moved in.

How does this explain how a heavy thing moves downwards?

The more decompressed and void a thing is, the quicker it will move upwards.

• If it were completely void it would move with a maximum speed!

But perhaps even this is impossible for it to move at all.

In the void, all things are incapable of moving.

This shows that the void cannot move, viz. the fact that the speeds are incomparable.

Some say that there is a void because if compression and decompression does not exist, then either:

• there will be no movement
• the universe will bulge, or
• a transformation of water into air will always be balanced by an equal transformation of air into water

(for it is clear that the air produced from water is bulkier than the water)

If compression does not exist, then either:

• the next portion will be pushed outwards and make the outermost part bulge, or
• somewhere else there must be an equal amount of water produced out of air
• In this way, the entire bulk of the whole may be equal, or that nothing moves.

When anything is displaced, this will always happen, unless it comes around in a circle.

But locomotion is not always circular, but sometimes in a straight line.

I deny that a void exists.

This is based on the assumption that:

• there is a single matter that then leads to contraries, such as hot and cold
• what exists actually is produced from a potential existence
• matter is not separable from the contraries but its being is different
• a single matter may serve for colour and heat and cold.

The same matter also serves for both a large and a small body.

When air is produced from water, the same matter has become something different by becoming actually what it was potentially.

Water is produced from air in the same way.

The change is:

• sometimes from smallness to greatness
• sometimes from greatness to smallness

In both cases, it is the matter which is potentially that becomes actually smaller and actually larger:

• Large-volume air turning into a smaller volume.
• Small-volume air turning into a bigger volume.

The same matter becomes:

• actually hot from being cold [having hotness potential]
• actually cold from being hot [having coldness potential].

it was potentially both, so too

This means that the actually hot matter can be hotter [have potential for more hotness].

This is similar to the curve of a large circle becomes the curve of a smaller circle.

• Its curveness does not exist in anything that was not curved.

Likewise, a flame always has heat and whiteness.

• Heat is always related to flame.

It follows that the greatness and smallness, also, of the sensible volume are extended, not by the matter’s acquiring anything new, but because the matter is potentially matter for both larger and smaller.

In this way, the same thing is compressed and decompressed through 1 matter.

• The compressed is heavy
• The decompressed is light

The arc of a circle when contracted into a smaller space does not acquire a new part which is convex, but what was there has been contracted

Any part of fire that one takes will be hot.

This is the same with contraction and expansion of the same matter.

There are 2 types in each case, both in the dense and in the rare.

The heavy and hard are compressed.

The light and soft are decompressed.

Weight and hardness fail to coincide in the case of lead and iron.

Void does not exist either separate (either absolutely separate or as a separate element in the rare) or potentially.

This is unless we call movement as void.

At that rate, the matter of the heavy and the light, qua matter of them, would be the void.

This is because the compressed and decompressed produce:

• motion because of this contrariety.
• passivity and impassivity because of their hardness and softness i.e. not motion but qualitative change

In what sense does the void exist and not exist?