τὰ δὲ καθ᾽ αὑτὰ ὅσα μὴ τῷ ὑπάρχειν τῷ κινοῦντι ἢ κινουμένῳ μηδὲ τῷ μόριόν τι αὐτῶν κινεῖν 7 κινεῖσθαι.
α As anything which makes a red ball move indirectly causes its colour to move, since the ball cannot move without it, but it does not make the redness move by exercising direct pressure on it, like that which it exerts on its material mass as such.
> As the whole scythe is moved because the handles have been set in motion by the mower, PHYSICS, VIII. rv.
ARGUMENT (continued) The distinction of ἡ natural’ and ‘ unnatural’ applies to the agents of motion or change: the natural agent is that which is actually so-and-so operating on what is potentially so-and-so. Similarly the natural patient 1s that which is potentially of such and such a quality (quantity etc.). So an element, such as fire, is moved naturally by something else when its own inherent potentiality (of up- ward motion) is called into activity (a 20-80).
The reason why the agent of such changes is hard to dis- tinguish is that there is more than one stage of potentiality before we reach full activity, which follows upon the final stage in the absence of extraneous hindrance (a 80--Ὁ 18).
Our question is: why light and heavy things move to their proper places. The answer is: they have a natural tendency to move in their respective directions, which con- stitutes the essence of lightness or heaviness. But, as we have seen, there is more than one stage of potentiality, and the final activity—actual motion to the proper place— may be hindered by an obstacle. To remove the obstacle is to * cause’ the motion only in an incidental sense. What is clear is that the things in question are not self-moved, but possess the quality of being set in motion by a suitably situated agent (Ὁ 13-31).
Conclusion: It is true in the case of all the four classes of things subject to motion or change, that they are moved or changed by some agent distinguishable from themselves Tuat which produces motion or in which motion is produced may be the immediate seat of the action or passion in question, in which case it is, itself, the primary and proper mover or moved; or it may be involved by implication either because it is implicated in the proper mover or moved, as the subject in which it inheres,* or because it is a whole of which the proper mover or moved is a part.?
VOL. II X 305 ARISTOTLE 254b Τῶν δὲ καθ᾽ αὑτὰ τὰ μὲν ὑφ᾽ ἑαυτοῦ τὰ δὲ ὑπ᾽ ἄλλου, καὶ τὰ μὲν φύσει τὰ δὲ Bia καὶ παρὰ φύσιν. 1 τότε yap αὐτὸ ὑφ᾽ αὑτοῦ κινούμενον φύσει κινεῖται, Ὄ 7 ἴω ῳω ~ οἷον ἕκαστον τῶν ζῴων: Kiwetras yap τὸ ζῷον αὐτὸ th αὑτοῦ, ὅσων δ᾽ ἡ ἀρχὴ ἐν αὐτοῖς τῆς κινήσεως, ταῦτα φύσει φαμὲν κινεῖσθαι. διὸ τὸ μὲν ζῷον ὅλον φύσει αὐτὸ EavTo κινεῖ, TO μέντοι σῶμα ἐνδέχεται καὶ φύσει Kat παρὰ φύσιν κινεῖσθαι" διαφέρει yap 20 ὁποίαν TE ἂν κίνησιν κινούμενον τύχῃ Kal ἐκ ποίου στοιχείου συνεστηκός. καὶ τῶν ὑπ᾽ ἄλλου κινου- μένων τὰ μὲν φύσει κινεῖται τὰ δὲ παρὰ φύσιν--- παρὰ φύσιν μὲν οἷον τὰ γεηρὰ ἄνω καὶ τὸ πῦρ κάτω. ἔτι δὲ TA μόρια TOV ζῴων πολλάκις κινεῖται παρὰ φύσιν, παρὰ τὰς θέσεις Kat τοὺς τρόπους τῆς ο5 κινήσεως. καὶ μάλιστα τὸ ὑπὸ τινος κινεῖσθαι τὸ κινούμενον ἐν τοῖς παρὰ φύσιν κινουμένοις ἐστὶ φανερὸν διὰ τὸ δῆλον εἶναι ὑπ᾽ ἄλλου κινούμενον. μετὰ δὲ TA παρὰ φύσιν τῶν κατὰ φύσιν τὰ αὐτὰ ὑφ᾽ αὑτῶν, οἷον τὰ ζῷα: οὐ γὰρ τοῦτ᾽ ἄδηλον, εἰ ὑπό α [attitudes: a man may walk on his hands; modes of motion: he may roll along on the ground instead of walking (Simplicius).—C. ] » This elaborate expansion of τὸ ὑπό τινος κινεῖσθαι τὸ κινούμενον is intended to bring out the important distinc- tion between a thing that has been set in motion, having had a cause to initiate that motion, and what Aristotle unhappily regards as the fact that whatever is in a state of motion must so long as it is moving be under continuous and direct action of its moving cause. On this devastating failure on Aristotle’s part to recognize the principle of inertia οὐ. Vol. 1.
PHYSICS, VIII. tv.
Of the proper subjects of motion some are moved xy themselves and others by something not them- selves, and some have a movement natural to them- selves and others have a movement forced upon them which is not natural to them. Thus the self- moved has a natural motion. Take, for instance, any animal: the animal moves itself, and we call every movement natural, the principle of which is internal to the body in motion. Wherefore the animal, as an organic whole, can only be moved by itself according to movements natural to it, whereas its body (considered apart from its vital force) may be moved on the lines natural to it or such as do it violence. It all depends on the nature of the movement and the elements of which the body is composed. So also in things that are not animate and do not move themselves it is possible for movements to be produced not only in harmony with their nature but in opposition to it, as when earth is made to move upwards and fire to move downwards. Moreover the several limbs of animals are often moved contrary to their nature in con- sequence of their attitudes and the modes of motion in question.* Now the fact that an object in motion must be under the present influence of something that is acting upon it ὃ is most obvious in the case of unnatural movements, for then it is plain that the motion is caused by an external agent. And after forced movements the next most obvious example of the same principle is those natural movements in which a thing in motion is being moved by itself, to wit the natural movements of animals; for in these cases there is no doubt as to there being an active factor in the animal that ARISTOTLE 254b τινος κινεῖται, ἀλλὰ πῶς δεῖ διαλαβεῖν αὐτοῦ τὸ 80 κινοῦν καὶ τὸ κινούμενον" ἔοικε γὰρ ὥσπερ ἐν τοῖς πλοίοις καὶ τοῖς μὴ φύσει συνισταμένοις, οὕτω καὶ ἐν τοῖς ζῴοις εἶναι διῃρημένον τὸ κινοῦν καὶ TO κινούμενον, καὶ οὕτω TO ἅπαν αὐτὸ αὑτὸ κινεῖν. Μάλιστα δ᾽ ἀπορεῖται τὸ λοιπὸν τῆς εἰρημένης τελευταίας διαιρέσεως" τῶν yap ὑπ᾽ ἄλλου Kwov- 8 μένων τὰ μὲν παρὰ φύσιν ἐθήκαμεν κινεῖσθαι, τὰ 2584 δὲ λείπεται ἀντιθεῖναι ὅτι φύσει. ταῦτα δ᾽ ἐστὶν ἃ τὴν ἀπορίαν παράσχοι ἂν ὑπὸ τίνος κινεῦται, οἷον τὰ κοῦφα καὶ τὰ βαρέα. ταῦτα γὰρ εἰς μὲν τοὺς ἀντικειμένους τόπους βίᾳ κινεῖται, εἰς δὲ τοὺς οἰκείους---τὸ μὲν κοῦφον ἄνω, τὸ δὲ βαρὺ KaTw— ο φύσει: τὸ δ᾽ ὑπὸ τίνος οὐκέτι φανερόν, ὥσπερ ὅταν κινῶνται παρὰ φύσιν. Τό τε yap αὐτὰ td αὑτῶν φάναι ἀδύνατον" ζωτικόν τε yap τοῦτο καὶ τῶν ἐμψύχων ἴδιον, Kal ἱστάναι ἂν ἐδύνατο αὑτά (λέγω δ᾽ οἷον, εἶ τοῦ α So that by definition it is only incidentally that the animal moves itself.
PHYSICS, VIII. rv.
is causing movement and a passive one that is experiencing it. The only problem is clearly to demark what factor in the animal it is that is in the proper and primary sense the producer of the movement and what that in which the movement is primarily and directly produced; for it would appear that what is obvious with a man-in-a-boat, or wherever we are dealing with things not naturally organized as wholes, is also really true with animals, viz. that we must distinguish between that which moves and that which is moved and can only say that the whole animal moves itself because both mover and moved are parts of that whole self.¢ The real difficulty then is narrowed down to those movements of things that are not self-moving which we have not yet dealt with; for in pronouncing some of the movements of things which are not self-moving to be contrary to their nature, we have by inference laid down that the rest are natural; and it is here that we come to grips with the real difficulty, viz. the question what is the agent of the natural movements of bodies heavy and light. For such bodies can be forced to move in directions opposite to those natural to them; but whereas it is obvious that light things go up and heavy ones down ‘by nature,’ we have not yet arrived at any clear conception as to what is the agent of this ‘natural’ movement, as we have done in the case of the enforced and unnatural movements.
For we cannot say that such bodies, when moving naturally, “move themselves,’ for this is proper to animals that have life, and if light and heavy bodies moved themselves up and down they would be able to stop themselves also—I mean that if an animal ARISTOTLE 255a βαδίζειν αἴτιον αὑτῷ, καὶ τοῦ μὴ βαδίζειν), ὥστ᾽ 1. εἰ ἐπ᾿ αὐτῷ TO ἄνω φέρεσθαι τῷ πυρί, δῆλον ὅτι ἐπ᾿ αὐτῷ καὶ τὸ κάτω. ἄλογον δὲ καὶ TO μίαν κίνησιν κινεῖσθαι μόνην ὑφ᾽ αὑτῶν, εἴγε αὐτὰ ἑαυτὰ κινοῦσιν. ἔτι πῶς ἐνδέχεται συνεχές τι καὶ συμφυὲς αὐτὸ ἑαυτὸ κινεῖν; ἧ yap ὃν Kal συνεχὲς μὴ ἁφῇ, ταύτῃ ἀπαθές" ἀλλ᾽ ἧ κεχώρισται, 1s ταύτῃ τὸ μὲν πέφυκε ποιεῖν τὸ δὲ πάσχειν. οὔτ᾽ ε “a lon dpa τούτων οὐθὲν αὐτὸ ἑαυτὸ κινεῖ--συμφυῆ yap— οὔτ᾽ ἄλλο συνεχὲς οὐδέν, ἀλλ᾽ ἀνάγκη διῃρῆσθαι τὸ κινοῦν ἐν ἑκάστῳ πρὸς τὸ κινούμενον, οἷον ἐπὶ τῶν ἀψύχων ὁρῶμεν, ὅταν κινῇ τι τῶν ἐμψύχων αὐτά. ἀλλὰ συμβαίνει καὶ ταῦτα ὑπό τινος ἀεὶ 20 Κινεῖσθαι: γένοιτο δ᾽ ἂν φανερὸν διαιροῦσι τὰς / αἰτίας. ἔστι δὲ καὶ ἐπὶ τῶν κινούντων λαβεῖν τὰ εἰρημένα: τὰ μὲν yap παρὰ φύσιν αὐτῶν κινητικά ἐστιν---οἷον ὁ μοχλὸς od φύσει τοῦ βάρους κινητικός --τὰ δὲ φύσει, οἷον τὸ ἐνεργείᾳ θερμὸν κινητικὸν α [Or ‘could only move with a single kind of motion,’ whereas an animal can walk, run, leap, dance and move up or down (Themistius). As the text stands, this sentence seems to contain a separate objection, though the logic would be improved if the clause ὥστ᾽ ef...τὸ κάτω (Il. 9-10) were transposed after ἑαυτὰ κινοῦσιν (]. 11).—C.]
¢ [Or ‘So none of these things (such as fire etc., which have a natural motion) moves itself—for they are of naturally coherent substance (cf. De gen. et corr. 327 a 1 συμφυὲς ἕκαστον καὶ ἕν ὃν dradés)—nor yet does anything else that is continuous, but the moving element in every case must be distinct from the moved, with such a distinction as can be actually seen in the case of an inanimate object (e.g. a boat) moved by an animate (a man rowing it).—C.]
PHYSICS, VIII. rv.
PHYSICS, VIII. rv.
can make itself march it can also make itself stop marching—so that if fire makes itself move upwards it should be able to make itself move downwards also. If they moved themselves there would be no sense in saying that they could only move in one direction? Again what can be meant by ἃ continuous and homogeneous body ‘ moving itself’? For in so far as it is one and continuous (otherwise than by contact ὃ) it cannot be affected by itself; it is only if it can be analysed into parts or factors that it can be self-affected, by one of its elements being the agent and another the patient. 9 Thus in the movement of such bodies there is no single constituent which is at once the primary agent and the primary patient (nor can there be, since each constituent is homogeneous in itself). And the argument applies to all properly ‘ continuous ’ bodies. So in every case the mover and the moved must be distinguished, just as we see that they are when a living thing as agent moves a lifeless thing as patient. These continuous bodies are, in fact, always moved by something else; what this some- thing is would become clear if we were to distinguish the causes involved.
The above-mentioned distinctions can be drawn in the case of the agents of motion: some of them are capable of causing motion unnaturally (a lever, for instance, is not by nature capable of moving a load “), others naturally; thus a body that is actually hot is capable of causing a change in one that is 4 A bar of iron is heavy, and so its inherent tendency is to pull or push things downwards. But it may be used as a lever and so made to impart a motion contrary to its own nature.
ARISTOTLE 25a τοῦ δυνάμει θερμοῦ: ὁμοίως δὲ Kat ἐπὶ τῶν ἄλλων 2 τῶν τοιούτων. καὶ κινητὸν δ᾽ ὡσαύτως φύσει τὸ δυνάμει ποιὸν ἢ ποσὸν 7% που, ὅταν ἔχῃ τὴν κιἃὦ A ἀρχὴν τὴν τοιαύτην ἐν αὑτῷ καὶ μὴ κατὰ συμ- βεβηκός (εἴη γὰρ ἂν τὸ αὐτὸ καὶ ποιὸν καὶ ποσόν, ἀλλὰ θατέρῳ θάτερον συμβέβηκε καὶ οὐ καθ᾽ αὑτὸ ὑπάρχει). τὸ δὴ πῦρ καὶ ἡ γῆ κινοῦνται ὑπό τινος 30 Bia μέν, ὅταν παρὰ φύσιν, φύσει δέ, ὅταν εἰς τὰς αὑτῶν ἐνεργείας δυνάμει ὄντα. met δὲ TO δυνάμει πλεοναχῶς λέγεται, τοῦτ αἴτιον τοῦ μὴ φανερὸν εἶναι ὑπὸ Tivos τὰ τοιαῦτα κινεῖται, οἷον τὸ πῦρ ἄνω καὶ ἡ γῆ κάτω. ἔστι δὲ δυνάμει ἄλλως ὃ μανθάνων ἐπιστήμων καὶ ὁ ἔχων ἤδη καὶ μὴ θεωρῶν. ἀεὶ δ᾽, ὅταν ἅμα τὸ 85 ποιητικὸν καὶ TO παθητικὸν ὦσι, γίγνεται ἐνίοτε 255 b ἐνεργείᾳ τὸ δυνατόν, οἷον τὸ μανθάνον ἐκ δυνάμει εἰ; ὄντος ἕτερον γίγνεται δυνάμει: ὁ γὰρ ἔχων ἐπι- στήμην μὴ θεωρῶν δὲ δυνάμει ἐστὶν ἐπιστήμων πως, ἀλλ᾽ οὐχ ὡς Kal πρὶν μαθεῖν. ὅταν δ᾽ οὕτως ἔχῃ, ἐὰν μή τι κωλύῃ, ἐνεργεῖ καὶ θεωρεῖ, ἢ ἔσται * TI follow Simplicius in understanding this to be the implication of ἐνίοτε. The alternative would be to omit it with IF and the copies reported by Alexander (Simplic. 1214.10). [Cf note in Oxford Translation. The apparent contradiction between dei and ἐνίοτε can be explained by taking the sentence (as above) to mean ‘ It is a rule without exception (def) that, agent and patient being in contact, under certain (i.e. favourable) circumstances (éviore) etc.’ Cf. the use of def at 266 a 26. The circumstances are un- favourable, if action is prevented by some extraneous obstacle (cf. Ὁ 4 ἐὰν μή τι κωλύῃ).---Ο,} PHYSICS, VIII. rv.
potentially hot; and so with other kinds of change. And it is the same with what is capable of suffering change: the natural subject of change is that which is potentially of a certain quality or quantity or in a certain place, when it contains the principle of the modification in question in itself and not accident- ally—‘ not accidentally,’ because a thing that comes to have a certain quality may also grow to a certain size at the same time, but the change of size is incidental to the change of quality and is not an essential property of the thing qua capable of quali- tive change. So, then, when fire and earth are moved by some agent, whereas the motion is forcible when it is contrary to their nature, it is natural when they actually engage in their proper move- ments, the potentiality for which was already in- herent in them.
Now the reason why the agent of such movements as that of fire upwards and earth downwards is not obvious is this: there are different stages of potenti- ality. The learner is a potential thinker in any given science in a different sense from that in which he is a potential thinker in it when he has learned its principles but is not thinking about it. And whenever the agent and patient are in effective 4 contact some kind of potentiality is developed into actuality; for instance the learner rises to a higher kind of potentiality, which he did not actually possess at first, for the expert’s expertness is still in a sense a potentiality rather than an actuality when he is not exercising it, but not in the same sense as it was before he had learned the skill. When he has acquired this second degree of potenti- ality he will actualize it in the positive exercise of ARISTOTLE ARISTOTLE 25b5 ev TH ἀντιφάσει καὶ ἀγνοίᾳ. ὁμοίως δὲ ταῦτ᾽ EXEL καὶ ἐπὶ τῶν φυσικῶν: τὸ γὰρ ψυχρὸν δυνάμει θ 4 ν δὲ ἐλ ἠδ “a φ ὃ ὔ av ερμόν, ὅταν δὲ μεταβάλῃ, ἤδη πῦρ, καίει δέ, ἂν μὴ τι κωλύῃ καὶ ἐμποδίζῃ. ὁμοίως δ᾽ ἔχει καὶ περὶ τὸ βαρὺ καὶ κοῦφον": τὸ γὰρ κοῦφον γίγνέται 10 ἐκ βαρέος, οἷον ἐξ ὕδατος ἀήρ" τοῦτο γὰρ δυνάμει πρῶτον, καὶ ἤδη κοῦφον, καὶ ἐνεργήσει γ᾽ εὐθύς, av μή TL κωλύῃ: ἐνέργεια δὲ τοῦ κούφου τὸ ποὺ εἶναι καὶ ἄνω, κωλύεται δ᾽ ὅταν ἐν τῷ ἐναντίῳ τόπῳ ἢ. καὶ τοῦθ᾽ ὁμοίως ἔχει Kal ἐπὶ τοῦ ποσοῦ καὶ ἐπὶ τοῦ ποιοῦ. Καίτοι τοῦτο ζητεῖται, διὰ τί ποτε κινεῖται εἰς 15 τὸν αὑτῶν τόπον τὰ κοῦφα καὶ τὰ βαρέα. αἴτιον ὅτι πέφυκέ ποι, καὶ τοῦτ᾽ ἐστὶ τὸ κούφῳ Kal βαρεῖ εἶναι, τὸ μὲν τῷ ἄνω τὸ δὲ τῷ κάτω διωρισμέ- νον. δυνάμει δ᾽ ἐστὶ κοῦφον καὶ βαρὺ πολλαχῶς, ὥσπερ εἴρηταν' ὅταν τε γὰρ ἦ ὕδωρ, δυνάμει γέ πώς ἐστι κοῦφον, καὶ ὅταν ἀήρ, ἔστιν ἔτι δυνάμει: 20 ἐνδέχεται γὰρ ἐμποδιζόμενον μὴ ἄνω εἶναι, ἀλλ ἐὰν ἀφαιρεθῇ τὸ ἐμποδίζον, ἐνεργεῖ καὶ ἀεὶ ἀνωτέρω γίγνεται. ὁμοίως δὲ καὶ τὸ ποιὸν εἰς τὸ ἐνεργείᾳ εἶναι μεταβάλλει" εὐθὺς γὰρ θεωρεῖ τὸ ἐπιστῆμον, ; ἂν μή τι κωλύῃ. καὶ τὸ ποσὸν ἐκτείνεται, ἐὰν μὴ τι κωλύῃ. ὃ δὲ TO ὑφιστάμενον καὶ κωλῦον 2 κινήσας ἔστι μὲν ὡς κινεῖ ἔστι δ᾽ ὡς οὔ, οἷον ὃ α Not continuously, but whenever he sees sufficient cause. Aristotle omits this qualification because his mind has already travelled on to the case of light and heavy bodies in which the challenge to the patient to actualize its potentiality 4s continuous.
PHYSICS, VIII. iv.
his power ὁ (unless there is some obstacle), else he were still in the ignorance which is the contradiction of this higher potentiality. Now this later stage of potentiality is what we meet in Physics; for the cold which is potentially hot, when it has completed the change and is effectively fire, actualizes its new potentiality and burns things, if not prevented. And so with heavy and light; for the light is de- veloped out of the heavy, as air out of water, for it too is at first (as water) only potentially light, but then (as air) becomes effectively light, and straight- way actualizes its new potentiality, unless hindered. The actuality of a light thing is to be somewhere, namely above, and the hindrance is whatever keeps it below. The analogy holds for quality and quan- tity as well as for position.
If the question is still pressed why light and heavy things tend to their respective positions, the only answer is that they are natured so, and that what we mean by heavy and light as distinguished and defined is just this downward or upward tendency. As we have said, here too there are different stages of potentiality. When a substance is water it is already in a way potentially light, and when it is air it may still be only potentially in the position proper to it, for its ascent may be hindered, but if the hindrance be removed it actualizes the potentiality and continuously mounts. And likewise the potenti- ally ‘ such’ tends to its actual realization; even as knowledge becomes straightway active if not im- peded; and so likewise are the potential dimensions of a thing realized if there be no hindrance. If anyone removes the obstacle he may be said in one sense (but in another not) to cause the movement; ARISTOTLE 255b τὸν κίονα ὑποσπάσας ἢ ὁ τὸν λίθον ἀφελὼν ἀπὸ τοῦ ἀσκοῦ ev τῷ ὕδατι: κατὰ συμβεβηκὸς yap κινεῖ, ὥσπερ καὶ ἡ ἀνακλασθεῖσα σφαῖρα ody ὑπὸ τοῦ τοίχου ἐκινήθη ἀλλ᾽ ὑπὸ τοῦ βάλλοντος. ὅτι μὲν τοίνυν οὐδὲν τούτων αὐτὸ κινεῖ ἑαυτό, δῆλον" 40 ἀλλὰ κινήσεως ἀρχὴν ἔχει, οὐ τοῦ κινεῖν οὐδὲ τοῦ ποιεῖν, ἀλλὰ τοῦ πάσχειν. Ei δὴ πάντα τὰ κινούμενα ἢ φύσει κινεῖται ἢ παρὰ φύσιν καὶ Bia, καὶ τά τε Bia καὶ παρὰ φύσιν πάντα ὑπό τινος καὶ ὑπ᾽ ἄλλου, τῶν δὲ φύσει πάλιν 96 TA θ᾽ ὑφ᾽ αὑτῶν κινούμενα ὑπό τινος κινεῖται καὶ δε Te μὴ ὑφ᾽ αὑτῶν (οἷον τὰ κοῦφα Kat τὰ βαρέα" ἢ γὰρ ὑπὸ τοῦ γεννήσαντος καὶ ποιήσαντος κοῦφον ἢ βαρύ, ἢ ὑπὸ τοῦ τὰ ἐμποδίζοντα καὶ κωλύοντα λύσαντος), ἅπαντα ἂν τὰ κινούμενα ὑπό τινος κινοῖτο.
PHYSICS, VIII. rv.
for instance if he removes a column from beneath the weight it was supporting, or cuts the string that attached a bladder, under water, to the stone that holds it down, for he incidentally determines the moment at which the potential motion becomes actual, just as the wall from which a ball rebounds determines the direction in which the ball rebounds, though it is the player and not the wall that is the cause of its motion. So it is now clear that in no one of these cases does the thing that is in motion move itself; but it has the passive (though not the active and efficient) principle of movement in- herent in itself.
Since then all things that are in motion either move according to their proper nature or in viola- tion of it and under compulsion; and all things whose movement is unnatural are set in motion by some agent external to them; and things whose movement is natural are also set in motion by some agent, whether (like animals) they move themselves (in the sense that they embrace both the active and the passive factors of motion in their organism), or do not move themselves, as for instance light and heavy substances, which are moved either directly by what agent soever generates them and makes them light or heavy, or incidentally by the agent that removes the obstruction or hindrance— if all this is so, I say it follows that all things in motion are moved by some agent.
ARISTOTLE CHAPTER V ARGUMENT [Zt will now be shown that the primary agent of motion is itselfunmoved. We have said that whatever is in motion must be moved by some agent. This may be either an intermediate, itself moved by the agent proper, or the agent proper, which may act either directly on the thing moved or through one or more intermediates (256 a 4-13).
If the agent is always something that is in motion, since there cannot be an infinite serves of intermediates which both move something and are moved by something else, the series must terminate in a first moved mover which is moved not by anything else but by itself (a 18-21).
The same argument stated in another form (a 21-- 8).
Again, if whatever is in motion 1s moved by an agent that is itself moved by something else, this fact that the agent is so moved is either (a) accidental or (b) essential to its operation as agent. If (a) it is accidental, then it would be logically possible that at some time motion should not exist at all; but that we have disproved in chap. i. (Ὁ 8-18). If (Ὁ) it is essential to the agent that it should be moved by another, this motion must either be of the same kind as it imparts or of one of the other two kinds. Ether supposition leads to impossibilities (b 27-257 a 14).
Further it 1s impossible ta suppose that whatever is capable of causing motion must be capable of suffering tt (a 14-25).
Conclusion: There cannot be an unlimited series of agents 2804 Lotro δὲ διχῶς" ἢ γὰρ οὐ de αὑτὸ τὸ κινοῦν 5 ἀλλὰ δι ἕτερον ὃ κινεῖ τὸ κινοῦν, 7) δι᾿ αὑτό" καὶ τοῦτο ἢ πρῶτον μετὰ τὸ ἔσχατον is διὰ πλειόνων, οἷον ἡ βακτηρία κιψεῖ τὸν λίθον καὶ κινεῖται ὑπὸ τῆς χειρὸς κιψουμένης ὑπὸ τοῦ ἀνθρώπου, οὗτος δ᾽ οὐκέτι τῷ ὑπ > ἄλλου κινεῖσθαι. ἄμφω δὴ. κινεῖν φα- 10 μεν---καὶ τὸ τελευταῖον καὶ τὸ πρῶτον τῶν κινούν- PHYSICS, VIII. v.
CHAPTER V ARGUMENT (contenued) each moved by something else: the series must terminate in an agent which is either unmoved or self-moved (a 25-31).
We must next consider in what sense self-motion is possible. (1) A thing cannot move itself in its entirety. Jt must contain a factor that moves and a factor that is moved (a 31— b 13). (2) Zt cannot be that each factor moves the other, reci- procally (Ὁ 13-26). And what is primarily self-moving cannot contain a factor, or factors, that are self-moving (Ὁ 26-- 258 a1). Conclusion: Whatever is self-moved contains an unmoved moving factor and a moved factor (a 1-2).
This conclusion further elaborated (a 2-27).
Final conclusion: The primary agent of motion is un- moved (b 3-9).
<This conclusion is such as we should expect from general considerations (256 Ὁ 18-27).> See Vol. I. p. Ixvii.—C.]
Now the thing moved may be moved by the true agent either directly or by some intermediate which itself is moved by the true agent directly. And the true agent may immediately precede the inter- mediate agent which acts directly upon the patient, or there may be a chain of several intermediates. Thus the staff (used as a lever) which shifts a stone may itself be moved by the hand that in its turn is moved by the man whose hand it is. But the man is not moved by anything other than himself. Ac- cordingly we say both that the last in the chain of movers moves the load, and that the first does. But if pushed we should say that it is really the first α It must be remembered that, according to Aristotle, motion is not only initiated but has to be maintained by the present action of the agent. See Vol. I. p. 196, note ὁ.
ARISTOTLE 256a των---ἀλλὰ μᾶλλον τὸ πρῶτον᾽ ἐκεῖνο γὰρ κινεῖ τὸ τελευταῖον, ἀλλ᾽ οὐ τοῦτο τὸ πρῶτον, Kal ἄνευ μὲν τοῦ πρώτου τὸ τελευταῖον οὐ κινήσει, ἐκεῖνο ὃ ἄνευ τούτου, οἷον ἡ βακτηρία οὐ κινήσει μὴ κινοῦντος τοῦ ἀνθρώπου. t δὴ ἀνάγκη πᾶν τὸ κινούμενον ὑπό τινός τε is Κινεῖσθαι καὶ ἢ ὑπὸ κινουμένου ὑπ᾽ ἄλλου ἢ μή, Kat εἰ μὲν ὑπ᾽ ἄλλου κινουμένου, ἀνάγκη τι εἶναι κινοῦν ὃ οὐχ ὑπ᾽ ἄλλου πρῶτον, εἰ δὲ τοιοῦτο τὸ πρῶτον, οὐκ ἀνάγκη θάτερον (ἀδύνατον γὰρ εἰς ἄπειρον ἰέναι TO κινοῦν Kal κινούμενον ὕπ᾽ ἄλλου αὐτό τῶν yap ἀπείρων οὐκ ἔστιν οὐδὲν πρῶτον)--- 20 εἰ οὖν ἅπαν μὲν TO κινούμενον ὑπό τινος κινεῖται, τὸ δὲ πρῶτον κινοῦν κινεῖται μὲν οὐχ ὑπ᾽ ἄλλου δέ, ἀνάγκη αὐτὸ ὑφ᾽ αὑτοῦ κινεῖσθαι. ἜΣ δὲ Α δὸ A 3 \ ~ λό 3) τι δὲ καὶ ὧδε τὸν αὐτὸν τοῦτον λόγον ἔστιν ἐπελθεῖν. πᾶν γὰρ τὸ κινοῦν τί τε κινεῖ καὶ τινί: a 4 Cow ee, ~ oN NX ᾿ ” θ ἢ γὰρ αὑτῷ κινεῖ τὸ κινοῦν ἢ ἄλλῳ, οἷον ἄνθρωπος ἢ αὐτὸς ἢ τῇ βακτηρίᾳ, καὶ ὃ ἄνεμος κατέβαλεν 25 αὐτὸς ἢ ὃ λίθος ὃν ἔωσεν. ἀδύνατον δὲ κινεῖν ἄνευ τοῦ αὐτὸ αὑτῷ κινοῦντος TO ᾧ κινεῖ" ἀλλ᾽ εἰ μὲν αὐτὸ αὑτῷ κινεῖ, οὐκ ἀνάγκη ἄλλο εἷναι ᾧ α (Literally, ‘and if (it is moved) by something that is moved by something else, then there must be at the beginning of the series (πρῶτον) some mover not moved by something else, whereas if the immediate mover (τὸ πρῶτον) is of this description, there is no necessity for the other thing (for any intermediate between it and the thing moved).’ In either case we shall arrive—mediately or immediately—at a prime self-moved mover.—C.]
PHYSICS, VIII. v.
and original mover, for the first moves the last (mediately) but the last does not move the first at all; moreover it could not move anything without the primary mover, but the primary mover could move things without it. In our example the staff could not move the stone unless the man moved the staff itself.
If then everything that is in motion must be moved by something, and that something must either be moved in its turn by something else or not, 4and in the latter case it is the true agent and we need go no further, but in the other case we noust run it back until we do reach a primary mover not moved by something else (for it is impossible to run back to infinity through movers that are themselves moved by something else, for there is no beginning at all of such an unlimited series)—why then it follows that if everything that is in motion is moved by some agent, and if the primary agent itself is in motion but is not moved by anything else, it must be moved by zéself.
Or (reversing the order of the demonstration) we may repeat the argument in this way. Every mover sets something in motion by some instrumentality, either its own or other than its own: the man for instance either by the instrumentality of his own hand or by that of the staff, and the wind either by its own impact or by loosening a stone that moves whatever it may be. And when the primary mover employs an instrument sejunct from itself, that sejunct instrument cannot act without the primary mover that moves by its own instrumentality. But the primary mover can apply its own instrumentality without having to employ any other; whereas an VOL. II Y 321 ARISTOTLE 256 aKLVEL, AV O€ 7) ETEPOV TO W KLVEL, ἐστι TL O KLVYOEL οὐ τινὲ ἀλλ᾽ αὑτῷ, ἢ εἰς ἄπειρον εἶσιν. εἰ οὖν κινούμενόν TL κινεῖ, ἀνάγκη στῆναι Kal μὴ εἰς 30 ἄπειρον ἰέναι" εἰ yap ἡ βακτηρία κινεῖ TH κινεῖσθαι ὑπὸ τῆς χειρός, ἡ χεὶρ κινεῖ τὴν BaxTyplav: εἰ δὲ Kal ταύτην" ἄλλο κινεῖ, καὶ ταύτην ἕτερόν τι τὸ κινοῦν. ὅταν δή τινι κινῇ ἀεὶ ἕτερον, ἀνάγκη εἶναι πρότερον τὸ αὐτὸ αὑτῷ κινοῦν. εἰ οὖν κινεῖται μὲν τοῦτο, μὴ ἄλλο δὲ τὸ κινοῦν αὐτό, ἀνάγκη αὐτὸ αὑτὸ 256 b κινεῖν: ὥστε Kal κατὰ τοῦτον τὸν λόγον ἤτοι εὐθὺς τὸ κινούμενον ὑπὸ τοῦ αὑτὸ κινοῦντος κινεῦται, ἢ ἔρχεταί ποτε εἰς τὸ τοιοῦτον. Πρὸς δὲ τοῖς εἰρημένοις καὶ ὧδε σκοποῦσι ταὐτὰ συμβήσεται ταῦτα. εἰ γὰρ ὑπὸ κινουμένου κινεῖται δ τὸ κινούμενον πᾶν, ἤτοι τοῦτο ὑπάρχει τοῖς πράγ- μασι κατὰ συμβεβηκός, ὥστε κινεῖν μὲν κινούμενον, οὐ μέντοι διὰ τὸ κινεῖσθαι αὐτὸ ἀεί, ἢ οὔ, ἀλλὰ καθ᾽ αὑτό. πρῶτον μὲν οὖν εἰ κατὰ συμβεβηκός, οὐκ ἀνάγκη κινεῖσθαι τὸ κινούμενον" εἰ δὲ τοῦτο, δῆλον ὡς ἐνδέχεταί ποτε μηδὲν κινεῖσθαι τῶν ὄντων" 10 οὐ yap ἀναγκαῖον τὸ συμβεβηκός, ἀλλ᾽ ἐνδεχόμενον x a 3 μὴ εἶναι. ἐὰν οὖν θῶμεν τὸ δυνατὸν εἶναι, οὐδὲν 1 [ταύτην codd.: ταύτῃ conj. Oxf. Trans. If ταύτην is retained, the clause means: ‘if the hand itself is moved by something else (not by itself),’ i.¢. 1f we have not yet reached a self-moving mover, then there must be another mover, which is self-moved, beyond it and distinct from 1t.—C.]
¢ [i.e. an agent that is moved by something else. This is what the following dilemma will prove impossible. But (as appears from the conclusion 257 a 25) the possibility that the first agent may be moved by itself remains open, as well as the possibility that it is unmoved.—C.]
PHYSICS, VIII. v.
instrument sejunct from a primary must (to be in action) have somewhere behind it some primary agent (or the search for one would run back with no limit). If, then, the agent of motion is in motion itself, we must come to stand somewhere and not go on without limit; for if the staff moves the load because it is itself moved by the hand, the hand in- deed moved the staff, but if the hand itself is moved by something else, what moves the hand is in turn a distinct thing. However long the chain, therefore, of things that produce motion by an instrumentality other than their own, there must lie behind it an agent that produces the movement by its own in- strumentality. So that if this primary agent is in motion, and there is no agent behind it to set it in motion, it must of necessity be moving itself. So this line of argument again leads to the conclusion that if anything is in motion it must either be set in motion by a self-moving agent immediately, or must send us back through a chain of intermediaries until we come to such an agent.
Yet further, the same conclusions will result from another line of reasoning. For if it be true that everything that is in motion is moved by an agent that is in motion itself,* either (a) this is inherent in the relation of mover to moved, or (6) it is only through some incidental connexion, so that although the mover always is as a matter of fact in motion, it is not in its capacity as motor that itisso. But in this latter case (6), motion would not be an eternal necessity, and it immediately follows that there would be a possibility of a total cessation of motion in things, for a connexion that is incidental may possibly cease. Now if any supposition we ARISTOTLE ARISTOTLE 256b ἀδύνατον συμβήσεται, ψεῦδος δ᾽ ἴσως. ἀλλὰ τὸ κίνησιν μὴ εἶναι ἀδύνατον: δέδεικται yap πρότερον ὅτι ἀνάγκη κίνησιν ἀεὶ εἶναι. 13 [Καὶ εὐλόγως...ἀμιγὴς ὦν. 11 ᾿Αλλὰ μὴν εἰ μὴ κατὰ συμβεβηκὸς ἀλλ᾽ ἐξ ἀνάγκης κινεῖται τὸ κινοῦν, εἰ δὲ μὴ κινοῖτο οὐκ 80 ἂν κινοίη, ἀνάγκη TO κινοῦν, ἡ κινεῖται, ἤτοι οὕτω eof ς 12 Sd are eS a, κινεῖσθαι ὡς τὸ" κατὰ τὸ αὐτὸ εἶδος THs κινήσεως, ἢ καθ᾽ ἕτερον" λέγω δὲ ἤτοι TO θερμαῖνον καὶ αὐτὸ θερμαίνεσθαι Kat τὸ ὑγιάζον ὑγιάζεσθαι καὶ τὸ φέρον φέρεσθαι, ἢ τὸ ὑγιάζον φέρεσθαι, τὸ δὲ φέρον αὔξεσθαι. ἀλλὰ φανερὸν ὅτι ἀδύνατον- δεῖ 2514 γὰρ μέχρι TOV ἀτόμων διαιροῦντα λέγειν, οἷον εἴ τι διδάσκει γεωμετρεῖν, τοῦτο διδάσκεσθαι γεω- μετρεῖν TO αὐτό, ἢ εἰ ῥιπτεῖ, ῥιπτεῖσθαι τὸν αὐτὸν τρόπον τῆς ῥίψεως- ἢ οὕτω μὲν μή, ἄλλο δ᾽ ἔ 5 ἄλλου γένους, οἷον τὸ φέρον μὲν αὔξεσθαι, τὸ δὲ τοῦτο αὖξον ἀλλοιοῦσθαι ὕπ᾽ ἄλλου, τὸ δὲ τοῦτο ἀλλοιοῦν ἑτέραν τινὰ κινεῖσθαι κίνησιν. ἀλλ ἀνάγκη στῆναι: πεπερασμέναι γὰρ αἱ κινήσεις. τὸ δὲ πάλιν ἀνακάμπτειν καὶ τὸ ἀλλοιοῦν φάναι φέρε- 1 [The paragraph here omitted is transferred to the end of the chapter. See note 2 on p. 336.—C.] 2 [ὡς τὸ Oxf. Trans.: ὥστε τὸ E: ὥστε cett.—C.]
« {In Bk. VII. chap. i—C.]
PHYSICS, VIII. v.
choose to make is not inherently impossible, then no deductions legitimately drawn from it can be inherently impossible either, though they may be contrary to fact. But it is inherently impossible for all motion to cease, since we have proved @ the eternal necessity of its persistence.
But if on the other alternative (a) it is not in- cidentally but primarily and of necessity that the mover as such is itself in motion, so that if it were not in motion it would not cause motion, then of necessity the movement which the mover as such itself experiences must be either of the same order as that which it imparts or of some other. I mean that either the heater must itself be growing hot and the curative itself becoming healthy and what causes local transference be itself in local transit, or the curative be (say) in local transit, or that which causes local transference be itself in process of growth. But obviously this will not work. For we should have to carry it down into the furthest detail, to say for instance that the teacher of geometry must be in process of himself learning the very theorem of geometry he is teaching, or that the thrower must be in act of being himself thrown after the same fashion; or else (taking the other alternative) to say that one kind of change depends on another— for example that what causes local transference is itself growing and that whatever makes it grow is itself being modified, and what causes this modifica- tion is experiencing some other kind of change. But this can not go on indefinitely, for the orders of change are limited in number. And to suppose that (in our example) the producer of the modification in the thing that is growing is itself in local transit would ARISTOTLE