There are no Indivisible Atoms

19. How this works with Expansion

The nature of material substance or body consists solely in its being the aetherspace [something extended, having length, width, height]

Its aetherspace [length, width, height] does not differ from the length, width, height [extension] attributed to empty space,

Then it follows that it cannot:

in any way, occupy more space at one time than another
be expanded in any way other than by being filled with external content.

It also follows that a vessel has the same volume [as length, width, height] when it is full of gold, lead, or some other heavy and hard substance as when it contains only air and seems empty.

This is because the contents of a body depends only on its length, width, height [extension], which is always the same in a given vessel.

20. This means that there can be no atoms or indivisible small bodies

Some philosophers have imagined that atoms or indivisible particles exist.

Such particles must have length, width, height [be extended], no matter how small they are.

The length, width, height of atoms could still be divided.

This means that they are divisible.

Even if God had reduced a particle of matter to such an extreme smallness that it could not be divided, we could still not conclude that it is indivisible.

If it is not divisible then He would deprive Himself of the power to divide it.

Thus, the smallest particle that has length, width, height [is extended] can always be divided, because divisibility is inherent to its nature.

21. The length, width, and height [extension] of the world is indefinite

The extended matter* that makes up the universe has no bounds.

Superphysics Note

This is the 2nd Element, or Spatial Layer in Material Superphysics which includes spacetime and aetherspace

This is because wherever we imagine a limit, we can still picture beyond it to spaces indefinitely extended.

These are not imaginary spaces, but ones that we conceive to actually be as we imagine them.

Thus, they contain a body indefinitely extended.

This is because our idea of length, width, and height [extension] in any space is the true idea that we should have of body itself.

22. It also follows that the Earth and the Heavens are made of the same matter and that there cannot be multiple worlds

Even if there were an infinity of worlds, they would be made of this same matter.

It follows that there cannot be multiple worlds.

The nature of matter consists solely in having length, width, height [being something extended].

This [spatial] matter already occupies all the imaginable spaces where these other worlds could be.

We cannot discover within ourselves the idea of any other kind of matter.

Superphysics Note

The multiple ‘worlds’ here would mean universes that had totally different Physics. Descartes allows a multiverse with many universes, but those universes have similar Physics, and never totally different.

23. All the varieties found in matter depend on the movement of its particles

There is only one and the same matter throughout the entire universe.

We know it solely by the fact that it has lenght, width, height [is extended].

All the properties that we distinctly perceive in it relate to its capacity to:

be divided and moved according to its particles, and
receive all the different configurations we observe arising from the movement of its particles.

We can imagine mental divisions in this matter.

But our thought has no power to change it.

All the diversity of forms within it depends on local movement.

Philosophers have noted this, since they have said that nature is the principle of motion and rest.

“Nature” is that which causes bodies to be arranged in the way we observe them through experience.