On The Elements
- Because there are composite substances, there must be some first physical substance(s), element(s), from which they are composed.
- Because there are multiple composite substances, there must be multiple first substances to account for the diversity.
- Because substances are changed from one to the other, the elements must have contrary propria, according to their natures.
- Because the substances both act and are acted upon, but cannot be potential in the same way at the same time, there must be two pairs of contrary propria.
- Because there are now four combinations of the two sets of contrary propria, each contrary pair has a medium, which is both necessary and now sufficient to explain the substantial change which occurs in the universe.
- Because the contrary propria are of the first physical substances, the propria must be such as are applicable to body in general as sensible, and having a contrary.
- Because the elements change into each other, the propria must be such as can be imparted from one into the other. The propria matching those requirements are:
hot, (actively separates each kind from the others)
cold, (actively condenses all kinds together)
adaptable (more passive, reactive motion of shape; = “wet”), and
inflexible (less passive, reactive motion of shape; = “dry”).
- Because the elements change their shape, the theory that the elements are each represented by one of the Platonic Solids is false, as Aristotle points out.
- Because there would be an element composed of each pairing between the two contraries, there would be:
a hot & inflexible ( = “fire”), [note that normal fire is not "inflexible", as the elemental fire described here must be -- "fire" is used here only analogously, as is true for all]
a hot & adaptable ( = “air”),
a cold & adaptable ( = “water”), and
a cold & inflexible element ( = “earth”).
- Because nature is a principle of motion and rest, each unique element must have a natural motion which is unique.
- Because the elements are simple bodies, it is clear that they cannot have a natural motion which is a change of quantity.
- Because the elements have a unique natural motion, they must have a unique locomotion, since this is prior to any qualitative change.
- Because motion is finite in space, this locomotion must then be toward a natural place of rest.
- Because motion is defined relative to some other object at rest, and all relative motions to some prior frame of reference at rest, elemental motion, being the first logical natural motion in the universe, must be defined relative to the universe itself.
- Because one is prior to many, and the complete prior to the incomplete, a sphere is the first shape in three dimensions, and is prior to any other shape.
- Because the whole is logically prior to the part, the whole of the universe is prior to any point within it, and therefore its shape must be a sphere.
- Because the universe is finite and composed of point-like units, and is spherical in shape, there must be some point which is the center.
- Because elemental motion is relative to the universe itself, the element must have:
a motion toward the center and rest at the center (gravity), or
a motion toward the periphery and rest at the periphery (levity), or
a motion around the center & never at rest (orbit)
- always actualized, in continuous motion, or
a motion always at rest in any place (fixedness)
- always actualized, at rest.
(Aristotle, at least, seems to think both eternal motion and rest are natural motions.)
DETERMINATION OF NATURE:
- ‘Fire’ is the most active element, and thus naturally orbits.
- ‘Water’ is the most passive element, and thus naturally is fixed.
- ‘Air’ is closer to fire, and thus naturally has levity.
- ‘Earth’ is closer to water, and thus naturally has gravity.