4. In numbers, as for example, eight is divided into fours, again four into twos, then two into ones. One is an atom because it is indivisible. So also in case of the letters. For you divide a speech into words, words into syllables, the syllable into letters. The letter, the smallest part, is the atom and cannot be divided. The atom is therefore what cannot be divided, like the point in geometry....

Chapter 3. On the elements.

1. Hyle[341] is the name the Greeks apply to the first material of things, which is in no way formed, but has a capacity for all bodily forms, and out of it these visible elements are shaped. Wherefore they have derived their name from this source.[342] This hyle the Latins called materia, for the reason that everything in the rough from which something is made, is always called materia....

2. The Greeks moreover call the elements στοιχεῖα,[343] because they are akin to one another in the harmony of like quality and a sort of common character, for they are said to be allied with one another in a natural way, now tracing their origin from fire all the way to earth, now from earth all the way to fire, so that fire fades into air, air is thickened to water, water coarsened to earth, and again earth is dissolved into water, water refined into air, air rarefied into fire.

3. Wherefore all elements are present in all, but each of them has received its name from that which it has in greater degree. And they have been assigned by divine providence to the living creatures that are suited to them, for the Creator himself filled the heaven with angels, the air with birds, the sea with fish, the earth with men and other living creatures.

Chapter 5. On the parts of the heavens.

1. Ether is the place in which the stars are, and it signifies that fire which is separated on high from the whole universe. Ether is the element itself; and aethra is the glow of the ether and is a Greek word.

Chapter 7. On the air and the clouds.

1. Air is emptiness, having more rarity mixed with it than the other elements. Of it Virgil says:

Longum per inane secutus.