Proof That Everything in Motion Is Moved by Another — Aristotle, Physics (alternative version) 1#1, Greek & English

§1#1

H (textus alter) Απαν τὸ κινούμενον ἀνάγκη ὑπό τινος κινεῖσθαι. εἰ μὲν οὖν ἐν αὐτῷ μὴ ἔχει τὴν ἀρχὴν τῆς κινήσεως, φανερὸν ὅτι ὑφʼ ἑτέρου κινεῖται (ἄλλο γὰρ ἔσται τὸ κινοῦν)· εἰ δʼ ἐν αὐτῷ, εἰλήφθω ἐφʼ οὗ τὸ ΑΒ, ὃ κινεῖται μὴ τῷ τῶν τούτου τι κινεῖσθαι.¹ πρῶτον μὲν οὖν τὸ ὑπολαμβάνειν τὸ ΑΒ ὑφʼ αὐτοῦ κινεῖσθαι διὰ τὸ ὅλον τε κινεῖσθαι καὶ ὑπὸ μηθενὸς τῶν ἔξωθεν ὅμοιόν ἐστιν ὥσπερ ἂν εἴ τις τοῦ ΔΕ κινοῦντος τὸ ΕΖ καὶ αὐτοῦ κινουμένου ὑπολαμβάνοι² τὸ ΔΕΖ ὑφʼ αὐτοῦ κινεῖσθαι, διὰ τὸ μὴ συνορᾶν πότερον ὑπὸ ποτέρου κινεῖται, πότερον τὸ ΔΕ ὑπὸ τοῦ ΕΖ ἢ τὸ ΕΖ ὑπὸ τοῦ ΔΕ. ἔτι τὸ ὑφʼ αὐτοῦ κινούμενον οὐδέποτε παύσεται κινούμενον τῷ ἕτερόν τι στῆναι κινούμενον.³ ἀνάγκη τοίνυν, εἴ τι παύεται κινούμενον τῷ ἕτερόν τι στῆναι, αὐτὸ ὑφ᾿ ἑτέρου κινεῖσθαι. τούτου δὲ φανεροῦ γενομένου ἀνάγκη πᾶν τὸ κινούμενον κινεῖσθαι ὑπό τινος. ἐπεὶ γὰρ εἴληπται τὸ ΑΒ κινούμενον, διαιρετὸν ἔσται· πᾶν γὰρ τὸ κινούμενον διαιρετὸν ἦν. διῃρήσθω τοίνυν ᾗ τὸ Γ. ἀνάγκη δὴ τοῦ ΓΒ ἠρεμοῦντος⁴ ἠρεμεῖν καὶ τὸ ΑΒ. εἰ γὰρ μή, εἰλήφθω κινούμενον. τοῦ τοίνυν ΓΒ ἠρεμοῦντος κινοῖτο ἂν τὸ ΓΑ. οὐκ ἄρα καθʼ αὐτὸ κινεῖται τὸ ΑΒ. ἀλλʼ ὑπέκειτο καθʼ αὑτὸ κινεῖσθαι πρῶτον. δῆλον τοίνυν ὅτι τοῦ ΓΒ ἠρεμοῦντος ἠρεμήσει καὶ τὸ ΒΑ, καὶ τότε παύσεται κινούμενον. ἀλλʼ εἴ τι τῷ ἄλλο ἠρεμεῖν ἵσταται καὶ παύεται κινούμενον, τοῦθʼ ὑφ᾿ ἑτέρου κινεῖται. φανερὸν δὴ ὅτι πᾶν τὸ κινούμενου ὑπό τινος κινεῖται διαιρετόν τε γάρ ἐστιν πᾶν τὸ κινούμενον, καὶ τοῦ μέρους ἠρεμοῦντος ἠρεμήσει καὶ τὸ ὅλον. ἐπεὶ δὲ τὸ κινούμενον ὑπό τινος κινεῖται, ἀνάγκη καὶ τὸ κινούμενον πᾶν ἐν τόπῳ κινεῖσθαι ὑπʼ ἄλλου· καὶ τὸ κινοῦν τοίνυν ὑφʼ ἑτέρου, ἐπειδὴ καὶ αὐτὸ κινεῖται, καὶ πάλιν τοῦτο ὑφʼ ἑτέρου. οὐ δὴ εἰς ἄπειρον πρόεισιν, ἀλλὰ στήσεταί που καὶ ἔσται τι ὃ πρώτως αἴτιον ἔσται τοῦ κινεῖσθαι. εἰ γὰρ μή, ἀλλʼ εἰς ἄπειρον πρόεισιν, ἔστω τὸ μὲν Α ὑπὸ τοῦ Β κινούμενον, τὸ δὲ ὑπὸ τοῦ Γ,⁵ τὸ δὲ Γ ὑπὸ τοῦ Δ· καὶ τοῦτον δὴ τὸν τρόπον εἰς ἄπειρον προβαινέτω. ἐπεὶ οὖν ἅμα τὸ κινοῦν καὶ αὐτὸ κινεῖται, δῆλον ὡς ἅμα κινήσεται τό τε Α καὶ τὸ Β· κινουμένου γὰρ τοῦ Β κινηθήσεται καὶ τὸ Α· καὶ τὸ Β δὴ κινουμένου τοῦ Γ καὶ τὸ Γ τοῦ Δ. ἔσται τοίνυν ἅμα ἥ τε τοῦ Α κίνησις ⟨καὶ τοῦ Β⟩ καὶ τοῦ Γ καὶ τῶν λοιπῶν ἑκάστου. καὶ λαβεῖν τοίνυν αὐτῶν ἑκάστην δυνησόμεθα. καὶ γὰρ εἰ ἕκαστον ὑφʼ ἑκάστου κινεῖται, οὐθὲν ἧττον μία τῷ ἀριθμῷ ἡ ἑκάστου κίνησις, καὶ οὐκ ἄπειρος τοῖς ἐσχάτοις, ἐπειδήπερ τὸ κινούμενον πᾶν ἔκ τινος εῖς τι κινεῖται.

H (textus alter) Everything that is in motion must be moved by something. If, on the one hand, it does not have the principle of motion in itself, it is obvious that it is moved by something else (for the mover will be other than it). But if, on the other hand, it has it in itself, let AB be taken as that which is in motion, not by the fact that some part of it is in motion. First, then, to suppose that AB is moved by itself because the whole is in motion and is moved by nothing external, is like as if, when DE moves EZ and is itself in motion, someone should suppose that DEZ is moved by itself, because of not seeing clearly which of them is moved by which, whether DE by EZ or EZ by DE. Furthermore, that which is moved by itself will never cease being in motion by the fact that something else in motion has come to a stop. It is necessary, therefore, that if something ceases being in motion by the fact that something else has come to a stop, it is itself moved by something else. This having become clear, everything that is in motion must be moved by something. For since AB has been assumed to be in motion, it will be divisible; for everything that is in motion was divisible. Let it, then, be divided at C. It is indeed necessary that if CB is at rest, AB also is at rest. For if not, let it be assumed to be in motion. Then while CB is at rest, CA would be in motion. Therefore AB is not moved in virtue of itself. But it was assumed at first to be moved in virtue of itself. It is clear, then, that when CB is at rest, BA also will be at rest, and then it will cease being in motion. But if something stops and ceases being in motion by the fact that something else is at rest, this is moved by something else. It is clear, then, that everything that is in motion is moved by something; for everything that is in motion is divisible, and when the part is at rest, the whole also will be at rest. Since, however, that which is in motion is moved by something, everything that is in motion in place must also be moved by something else; and the mover, therefore, by something else, since it is itself also in motion, and this again by something else. It will not, indeed, proceed to infinity, but will stop somewhere, and there will be something which will be the primary cause of being moved. For if not, but it proceeds to infinity, let A be moved by B, and [B] by C, and C by D; and in this way let it proceed to infinity. Since, then, the mover and that which is itself in motion are simultaneous, it is clear that both A and B will be in motion simultaneously; for when B is in motion, A also will be moved, and B when C is in motion, and C when D is in motion. There will be, therefore, simultaneously the motion of A, and of B, and of C, and of each of the rest. We shall therefore be able to grasp each of them. For even if each is moved by each, the motion of each is none the less one in number, and not infinite at its extremes, since everything that is in motion is moved from something to something.

Syntax notes5 items

241b25μὴ τῷ τῶν τούτου τι κινεῖσθαι
The dative articular infinitive τῷ κινεῖσθαι ('by the being in motion') expresses means or cause, with the nominative pronoun τι ('something') as its subject. τῶν τούτου ('of these [parts] of it') is a partitive genitive. It specifies the condition of primary, direct self-motion, where the whole AB does not move merely because one of its parts is moving.
241b25ὥσπερ ἂν εἴ τις ... ὑπολαμβάνοι
The construction ὥσπερ ἂν εἰ + optative (υπολαμβάνοι) expresses a potential assumption or comparison ('just as if someone should suppose'). It introduces a hypothetical scenario to evaluate the validity of the thought experiment.
241b30τῷ ἕτερόν τι στῆναι κινούμενον
The articular infinitive in the dative without a preposition, τῷ στῆναι ('by the coming to a stop'), expresses cause or means, with the accusative ἕτερόν τι ('something else') as its subject. The participle κινούμενον modifies ἕτερόν τι, meaning 'by the fact that some other thing that is in motion comes to a stop'.
242a5τοῦ ΓΒ ἠρεμοῦντος
A genitive absolute construction, expressing a conditional clause here ('if CB is at rest'). This is a crucial step in the argument against self-motion, establishing the physical and logical necessity that the rest of a part entails the rest of the whole.
242a20τὸ δὲ ὑπὸ τοῦ Γ
The subject is omitted after τὸ δέ. From the parallelism with the preceding τὸ μὲν Α ὑπὸ τοῦ Β and the subsequent τὸ δὲ Γ ὑπὸ τοῦ Δ, it is clear that the omitted subject is B, which must be supplied in translation as [B].

Translated by Gemini 3.5 Flash (published 2026-05-22) · Revision history (1, latest 2026-09-22)

2026-09-22 AI review — source 1

urn:cts:greekLit:tlg0086.tlg054.humanitext-grc1:1#1