9

On their foundations.

...it observes the center or the plumb line as its natural place with a most constant order. Indeed, it is plain to the eye that this entire universe keeps its fixed and defined courses around the unmoving globe of the earth exactly and without straying. Aristotle's cosmology placed the Earth at the center of the universe, where all "heavy" things naturally fell.

But if that middle point, the center or nucleus, could be removed, there is no doubt that the world would fall forward through empty space into infinity due to its innate gravity. However, this disaster is easily prevented in the manner stated before.

Third, Aristotle says: If an infinite vacuum were given outside the world, the world would be ruined, disconnected, corrupted, and scattered in infinite ways.

Not at all! Cleomedes responds; because once its own property, power, and determined nature have been implanted in the world, its substance is preserved most constantly by that force, even against the nature and inclination of the vacuum. Cleomedes was a Stoic philosopher who argued that a "tension" or force held the physical world together against the pulling void.

By that unspeakable force, the parts of the world are joined most firmly. No matter how many changes and cycles they have within them, they can never be entirely separated or disturbed because of this innate support.

Fourth and finally, in the judgment of Cleomedes, it is false and not at all necessary for infinite bodies to exist just because the vacuum is infinite.

For certain things said about the vacuum or space being limited are not so easily applied to physical things. Because of their motion, physical things require some boundary and a determined place. By what logic can something that is surrounded and bounded by another thing be called infinite?

These, then, are the arguments with which Cleomedes tries to destroy Aristotle's opinion. We will pass over them here, as they contribute nothing to our present matter and purpose. Instead, we will briefly treat Hero’s opinion on the vacuum, which promises more usefulness in its explanation.

CHAPTER V.

HERO OF ALEXANDRIA

After the philosophers named above, Hero of Alexandria Hero, or Heron, was a 1st-century mathematician and engineer famous for his inventions and his work on pneumatics. brings a unique opinion onto the stage, saying: Many from the flock of the learned denied that a vacuum is found in the world. I, however, both grant and establish it. It is not indeed gathered together in one place, but scattered and sown here and there through water, air, fire, and other bodies in tiny, imperceptible particles.

For although a diamond adamas: the hardest known substance, described here as impenetrable, because of its innate hardness, cannot be penetrated by fire or iron, this is by no means because it lacks all vacuum. Rather, it is due to its most constant and uninjured hardness and its thick, dense, and indivisible substance.

For a full demonstration of this matter, one must know that air is a body composed of tiny, very light, and invisible particles or atoms. These cling to one another firmly, yet not on every side. They have empty little spaces mixed among them, like sand piled up or heaped on the seashore.

Imagine those little grains of sand to be the atoms or particles of air, while the intermixed breeze or airy matter represents the vacuum mentioned just now.