The Nature of Motion

It is impossible:

• for anything to be moved without a mover.
• for a mover to exist without something which can be moved

Motion cannot exist where either of these are lacking. It is for impossible for these to be uniform. Therefore we must assign rest to uniformity and motion to the lack of uniformity.

Inequality is the cause of the nature which is lacking in uniformity.

Why things when divided do not cease to pass through one another and to change their place?

In the revolution of the universe are comprehended all the 4 elements.

This is circular and having a tendency to come together. It compresses everything and will not allow any place to be left void.

Fire penetrates everywhere. Air goes next, as being next in rarity of the elements. The two other elements in like manner penetrate according to their degrees of rarity.

For those things which are composed of the largest particles have the largest void left in their compositions. Those which are composed of the smallest particles have the least.

The contraction caused by the compression thrusts the smaller particles into the interstices of the larger.

Thus, when the small parts are placed side by side with the larger, and the lesser divide the greater and the greater unite the lesser, all the elements are borne up and down and hither and thither towards their own places; for the change in the size of each changes its position in space.

These causes generate an inequality which is always maintained, and is continually creating a perpetual motion of the elements in all time.

Kinds of Fire

1. Flame
2. Emanations of flame which do not burn but only give light to the eyes
3. The remains of fire, which are seen in red-hot embers after the flame has been extinguished.

Air

There are similar differences in the air. The brightest part is called the aether. The most turbid sort mist and darkness. There are various other nameless kinds which arise from the inequality of the triangles.

Water

Water is divided into 2 kinds:

1. liquid

• small and unequal particles of water. This moves itself and is moved by other bodies owing to the want of uniformity and the shape of its particles

2. fusile.

• this is formed of large and uniform particles, is more stable than the other, and is heavy and compact by reason of its uniformity.

When fire gets in and dissolves the particles and destroys the uniformity, it has greater mobility, and becoming fluid is thrust forth by the neighbouring air and spreads upon the earth.

This dissolution of the solid masses is called “melting”. Their spreading out upon the earth flowing. Again, when the fire goes out of the fusile substance, it does not pass into a vacuum, but into the neighbouring air.

The air which is displaced forces together the liquid and still moveable mass into the place which was occupied by the fire, and unites it with itself.

Thus, compressed the mass resumes its equability, and is again at unity with itself, because the fire which was the author of the inequality has retreated; and this departure of the fire is called cooling, and the coming together which follows upon it is termed congealment.

Of all the kinds termed fusile, that which is the densest and is formed out of the finest and most uniform parts is that most precious possession called gold, which is hardened by filtration through rock; this is unique in kind, and has both a glittering and a yellow colour.

A shoot of gold, which is so dense as to be very hard, and takes a black colour, is called adamant.

There is also another kind which has parts nearly like gold, and of which there are several species. It is denser than gold. It contains a small and fine portion of earth, and is therefore harder, yet also lighter because of the great interstices which it has within itself.

This substance, which is one of the bright and denser kinds of water, when solidified is called copper.

There is an alloy of earth mingled with it, which, when the two parts grow old and are disunited, shows itself separately and is called rust. The remaining phenomena of the same kind there will be no difficulty in reasoning out by the method of probabilities.

A man may sometimes set aside meditations about eternal things, and for recreation turn to consider the truths of generation which are probable only.

He will thus gain a pleasure not to be repented of, and secure for himself while he lives a wise and moderate pastime. Let us grant ourselves this indulgence, and go through the probabilities relating to the same subjects which follow next in order.

Water which is mingled with fire, so much as is fine and liquid (being so called by reason of its motion and the way in which it rolls along the ground), and soft, because its bases give way and are less stable than those of earth, when separated from fire and air and isolated, becomes more uniform, and by their retirement is compressed into itself.

If the condensation be very great, the water above the earth becomes hail, but on the earth, ice; and that which is congealed in a less degree and is only half solid, when above the earth is called snow, and when upon the earth, and condensed from dew, hoar-frost.

There are many kinds of water which have been mingled with one another, and are distilled through plants which grow in the earth. This whole class is called by the name of juices or saps.

The unequal admixture of these fluids creates a variety of species; most of them are nameless, but four which are of a fiery nature are clearly distinguished and have names.

1. There is wine, which warms the soul as well as the body
2. There is the oily nature, which is smooth and divides the visual ray, and for this reason is bright and shining and of a glistening appearance, including pitch, the juice of the castor berry, oil itself, and other things of a like kind
3. There is the class of substances which expand the contracted parts of the mouth, until they return to their natural state, and by reason of this property create sweetness;—these are included under the general name of honey=
4. There is a frothy nature, which differs from all juices, having a burning quality which dissolves the flesh; it is called opos (a vegetable acid).

The kind of earth that is filtered through water passes into stone in the following way:

The water which mixes with the earth and is broken up in the process changes into air, and taking this form mounts into its own place.

But as there is no surrounding vacuum, it thrusts away the neighbouring air. This being rendered heavy, and when it is displaced, having been poured around the mass of earth, forcibly compresses it and drives it into the vacant space whence the new air had come up. The earth when compressed by the air into an indissoluble union with water becomes rock.

The fairer sort is that which is made up of equal and similar parts and is transparent; that which has the opposite qualities is inferior.

But when all the watery part is suddenly drawn out by fire, a more brittle substance is formed, to which we give the name of pottery. Sometimes also moisture may remain, and the earth which has been fused by fire becomes, when cool, a certain stone of a black colour.

A like separation of the water which had been copiously mingled with them may occur in 2 substances composed of finer particles of earth and of a briny nature; out of either of them a half-solid-body is then formed, soluble in water—the one, soda, which is used for purging away oil and earth, the other, salt, which harmonizes so well in combinations pleasing to the palate, and is, as the law testifies, a substance dear to the gods.

The compounds of earth and water are not soluble by water, but by fire only. This is because neither fire nor air melt masses of earth. This is because their particles are smaller than the interstices in its structure. They have plenty of room to move without forcing their way. And so they leave the earth unmelted and undissolved; but particles of water, which are larger, force a passage, and dissolve and melt the earth.

Wherefore earth when not consolidated by force is dissolved by water only; when consolidated, by nothing but fire; for this is the only body which can find an entrance.

The cohesion of water:

• when very strong, is dissolved by fire only.
• when weaker, then either by air or fire

Air enters the interstices, and the latter penetrating even the triangles.

But nothing can dissolve air, when strongly condensed, which does not reach the elements or triangles; or if not strongly condensed, then only fire can dissolve it.

While the water occupies the vacant interstices of the earth in them which are compressed by force, the particles of water which approach them from without, finding no entrance, flow around the entire mass and leave it undissolved.

But the particles of fire, entering into the interstices of the water, do to the water what water does to earth and fire to air (The text seems to be corrupt.), and are the sole causes of the compound body of earth and water liquefying and becoming fluid.

These bodies are of 2 kinds:

1. Some of them, such as glass and the fusible sort of stones, have less water than they have earth;
2. substances of the nature of wax and incense have more of water entering into their composition.