Humanitext Reader

Aristotle · On the Heavens §2.7

The Composition of Stars and the Cause of Their Heat and Light

Passage 30 of 62 · Greek

Summary

The author begins the inquiry into the composition, shape, and motion of the stars, arguing that they are composed of the same substance as the sphere in which they move, and that their heat and light are produced by the friction and subsequent ignition of the air below caused by their motion.

§2.77 Περὶ δὲ τῶν καλουμένων ἄστρων ἑπόμενον ἂν εἴη λέγειν, ἐκ τίνων τε συνεστᾶσι καὶ ἐν ποίοις σχήμασι καὶ τίνες αἱ κινήσεις αὐτῶν.
7 Next in order would be to speak of the so-called stars, of what they are composed, in what shapes, and what their movements are.
εὐλογώτατον δὴ καὶ τοῖς εἰρημένοις ἑπόμενον ἡμῖν τὸ ἕκαστον τῶν ἄστρων ποιεῖν ἐκ τούτου τοῦ σώματος ἐν ᾧ τυγχάνει τὴν φορὰν ἔχον, ἐπειδὴ ἔφαμέν τι εἶναι ὃ κύκλῳ φέρεσθαι πέφυκεν·
Indeed, it is most reasonable and consistent with what has been said for us to make each of the stars out of that body in which it happens to have its movement, since we said there is something which is naturally carried in a circle.
ὥσπερ γὰρ οἱ πύρινα φάσκοντες εἶναι διὰ τοῦτο λέγουσιν, ὅτι τὸ ἄνω σῶμα πῦρ εἶναί φασιν, ὡς εὔλογον ὂν ἕκαστον συνεστάναι ἐκ τούτων ἐν οἷς ἕκαστον ἐστίν, ὁμοίως καὶ ἡμεῖς λέγομεν.
For just as those who assert they are fiery say so for this reason, that they declare the upper body to be fire, as it is reasonable for each thing to be composed of those things in which each is, so we also say likewise.
ἡ δὲ θερμότης ἀπʼ αὐτῶν καὶ τὸ φῶς γίνεται παρεκτριβομένου τοῦ ἀέρος ὑπὸ τῆς ἐκείνων φορᾶς.
And the heat and the light from them arise as the air is rubbed by their movement.
πέφυκε γὰρ ἡ κίνησις ἐκπυροῦν καὶ ξύλα καὶ λίθους καὶ σίδηρον· εὐλογώτερον οὖν τὸ ἐγγύτερον τοῦ πυρός, ἐγγύτερον δὲ ἀὴρ οἷον καὶ ἐπὶ τῶν φερομένων βελῶν·
For motion is naturally capable of igniting wood, stones, and iron; it is more reasonable, then, that what is closer to fire should be ignited, and air is closer, as is also the case with flying missiles.
ταῦτα γὰρ αὐτὰ ἐκπυροῦται οὕτως ὥστε τήκεσθαι τὰς μολυβδίδας, καὶ ἐπείπερ αὐτὰ ἐκπυροῦται, ἀνάγκη καὶ τὸν κύκλῳ αὐτῶν ἀέρα τὸ αὐτὸ τοῦτο πάσχειν.
For these themselves are ignited in such a way that the leaden bullets melt, and since they themselves are ignited, it is necessary that the air around them also suffers this same thing.
ταῦτα μὲν οὖν ἐκθερμαίνεται διὰ τὸ ἐν ἀέρι φέρεσθαι, ὸς διὰ τὴν πληγὴν τῇ κινήσει γίγνεται πῦρ· τῶν δὲ ἄνω ἕκαστον ἐν τῇ σφαίρᾳ φέρεται, ὥστʼ αὐτὰ μὲν μὴ ἐκπυροῦσθαι, τοῦ δʼ ἀέρος ὑπὸ τὴν τοῦ κυκλικοῦ σώματος σφαῖραν ὄντος ἀνάγκη φερομένης ἐκείνης ἐκθερμαίνεσθαι, καὶ ταύτῃ μάλιστα ᾗ ὁ ἥλιος τετύχηκεν ἐνδεδεμένος.
Now these are heated because they are carried in the air, which becomes fire by the blow caused by the motion; but each of the things above is carried in its sphere, so that they themselves are not ignited, but the air being under the sphere of the circular body must be heated when that sphere is carried along, and most of all in that part where the sun happens to be fixed.
διὸ δὴ πλησιάζοντός τε αὐτοῦ καὶ ἀνίσχοντος καὶ ὑπὲρ ἡμᾶς ὄντος γίγνεται ἡ θερμότης.
For this reason indeed, as it approaches, rises, and is above us, the heat arises.
ὅτι μὲν οὖν οὔτε πύρινά ἐστιν οὔτ᾿ ἐν πυρὶ φέρεται, ταῦθʼ ἡμῖν εἰρήσθω περὶ αὐτῶν.
That, then, they are neither fiery nor carried in fire, let so much be said by us concerning them.

Notes

  1. §2.7τὸ ἕκαστον τῶν ἄστρων ποιεῖν ἐκ τούτου τοῦ σώματος — An articular infinitive clause "tὸ ... ποιεῖν" functioning as the subject of "εὐλογώτατον" and "ἑπόμενον". The phrase "ποιεῖν ἐκ" means "to assume or make something to be composed of some material". "ἡμῖν" is the dative of agent or reference ("for us").
  2. ¦15¦ὡς εὔλογον ὂν ἕκαστον συνεστάναι — An accusative absolute construction "ὡς εὔλογον ὂν" (using the neuter accusative singular of the participle of "εἶναι" with the impersonal adjective "εὔλογον"), introduced by "ὡς" to express subjective reason. The infinitive "συνεστάναι" acts as the subject of the impersonal phrase.
  3. ¦30¦τοῦ δʼ ἀέρος ... ὄντος ἀνάγκη φερομένης ἐκείνης ἐκθερμαίνεσθαι — This sentence contains nested genitive absolute constructions. The outer genitive absolute is "τοῦ δʼ ἀέρος ... ὄντος" (since the air is under the sphere...), within which "φερομένης ἐκείνης" (while that sphere is carried along) functions as another genitive absolute modifying the infinitive "ἐκθερμαίνεσθαι". "ἀνάγκη" functions as an impersonal predicate meaning "it is necessary", with the air ("τοῦ ἀέρος") as the subject of the infinitive.

Cite this passage

Aristotle, On the Heavens §2.7. Humanitext Reader, https://reader.humanitext.ai/en/text/urn:cts:greekLit:tlg0086.tlg005.humanitext-grc1:2.7

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