Chapter VIII.—Concerning air and winds.

Air is the most subtle element, and is moist and warm: heavier, indeed, than fire: but lighter than earth and water: it is the cause of respiration and voice: it is colourless, that is, it has no colour by nature: it is clear and transparent, for it is capable of receiving light: it ministers to three of our senses, for it is by its aid that we see, hear and smell: it has the power likewise of receiving heat and cold, dryness and moisture, and its movements in space are up, down, within, without, to the right and to the left, and the cyclical movement.

It does not derive its light from itself, but is illuminated by sun, and moon, and stars, and fire. And this is just what the Scripture means when it says, And darkness was upon the deep333    Gen. i. 2.; for its object is to shew that the air has not derived its light from itself, but that it is quite a different essence from light.

And wind is a movement of air: or wind is a rush of air which changes its name as it changes the place whence it rushes334    Sever. Gabal., Hom. 1 in Hexaëm..

Its place is in the air. For place is the circumference of a body. But what is it that surrounds bodies but air? There are, moreover, different places in which the movement of air originates, and from these the winds get their names. There are in all twelve winds. It is said that air is just fire after it has been extinguished, or the vapour of heated water. At all events, in its own special nature the air is warm, but it becomes cold owing to the proximity of water and earth, so that the lower parts of it are cold, and the higher warm335    Nemes., De Nat. Hom. i., ch. 5..

Περὶ ἀέρος καὶ ἀνέμων

Ἀήρ ἐστι στοιχεῖον λεπτότατον ὑγρόν τε καὶ θερμόν, τοῦ μὲν πυρὸς βαρύτερον, τῆς δὲ γῆς καὶ τῶν ὑδάτων κουφότερον, ἀναπνοῆς καὶ ἐκφωνήσεως αἴτιον, ἀχρωμάτιστον ἤτοι ἐκ φύσεως χρῶμα μὴ κεκτημένον, διειδές, διαφανές (φωτὸς γάρ ἐστι δεκτικόν) καὶ ταῖς τρισὶν αἰσθήσεσιν ἡμῶν διακονοῦν (δι' αὐτοῦ γὰρ ὁρῶμεν, ἀκούομεν, ὀσφραινόμεθα), δεκτικὸν θάλψεώς τε καὶ ψύξεως ξηρότητός τε καὶ ὑγρότητος, οὗ πᾶσαι αἱ κατὰ τόπον κινήσεις εἰσίν: ἄνω, κάτω, ἔσω, ἔξω, δεξιά, ἀριστερὰ καὶ ἡ κυκλοφορικὴ κίνησις. Οἴκοθεν μὴ κεκτημένος τὸ φῶς, ἀλλ' ὑπὸ ἡλίου καὶ σελήνης καὶ ἄστρων καὶ πυρὸς φωτιζόμενος. Καὶ τοῦτό ἐστιν, ὃ εἶπεν ἡ γραφή, ὅτι «σκότος ἦν ἐπάνω τῆς ἀβύσσου», θέλουσα δεῖξαι, ὡς οὐκ οἴκοθεν ὁ ἀὴρ τὸ φῶς κέκτηται, ἀλλ' ἄλλη τίς ἐστιν οὐσία ἡ τοῦ φωτός.

Ἄνεμος δέ ἐστι κίνησις ἀέρος. Καὶ ὁ τόπος δὲ τοῦ ἀέρος ἐστί: τόπος γάρ ἐστιν ἑκάστου σώματος ἡ τούτου περιοχή. Τί δὲ περιέχει τὰ σώματα, εἰ μὴ ἀήρ; Εἰσὶ δὲ τόποι διάφοροι, ὅθεν ἡ τοῦ ἀέρος γίνεται κίνησις, ἐξ ὧν καὶ οἱ ἄνεμοι τὰς ἐπωνυμίας ἔχουσι: δώδεκα δὲ οἱ πάντες εἰσί. Φασὶ δὲ τὸν ἀέρα σβέσιν πυρὸς ἢ ἀτμὸν ὕδατος θερμανθέντος. Ἔστι γοῦν ὁ ἀὴρ κατὰ μὲν τὴν οἰκείαν φύσιν θερμός, ψύχεται δὲ τῇ γειτνιάσει τῇ πρὸς τὸ ὕδωρ καὶ τὴν γῆν, ὡς τὰ μὲν κάτω μέρη αὐτοῦ ψυχρὰ εἶναι, τὰ δὲ ἄνω θερμά.