advance.[1] In fact, it makes the Milesian cosmology consistent for the first time; since a theory which explains everything as a form of a single substance is clearly bound to regard all differences as quantitative. The only way to save the unity of the primary substance is to say that all diversities are due to the presence of more or less of it in a given space. And when once this step has been taken, it is no longer necessary to make the primary substance something "distinct from the elements," to use Aristotle's inaccurate but convenient phrase; it may just as well be one of them.
27.Air. The air Anaximenes speaks of includes a good deal that we should not call by the name. In its normal condition, when most evenly distributed, it is invisible, and it then corresponds to our "air"; it is the breath we inhale and the wind that blows. That is why he called it πνεῦμα. On the other hand, the old idea that mist or vapour is condensed air, is still accepted without question. It was Empedokles, we shall see, who first discovered that what we call air was a distinct corporeal substance, and not identical either with vapour or with empty space. In the earlier cosmologists "air" is always a form of vapour, and even darkness is a form of "air." It was Empedokles who cleared up this point too by showing that darkness is a shadow.[2]
- ↑ Simplicius, Phys. p. 149, 32 (R. P. 26 b), says that Theophrastos spoke of rarefaction and condensation in the case of Anaximenes alone. It should be noted, however, that Aristotle, Phys. A, 4. 187 a 12, seems to imply that Anaximander too had spoken of rarefaction and condensation, especially if ὅ ἐστι πυρὸς μὲν πυκνότερον ἀέρος δὲ λεπτότερον is referred to him. On the other hand, at 20, οἱ δ' ἐκ τοῦ ἑνὸς ἐνούσας τὰς ἐναντιότητας ἐκκρίνεσθαι, ὥσπερ Ἀναξίμανδρός φησι seems to be opposed to a 12, οἱ μὲν κτλ. As I have indicated already, it looks as if we were dealing here with Aristotle's own inferences and interpretations, which are far from clear. They are outweighed by the definite statement quoted by Simplicius from Theophrastos, though Simplicius himself adds δῆλον δὲ ὡς καὶ οἱ ἄλλοι τῇ μανότητι καὶ πυκνότητι ἐχρῶντο. That, however, is only his own inference from Aristotle's somewhat confused statement.
- ↑ For the meaning of ἀήρ in Homer, cf. e.g. Od. viii. 1, ἠέρι καὶ νεφέλῃ κεκαλυμμέναι; and for its survival in Ionic prose, Hippokrates, Περὶ
