Chapter 61

Motion is the actualization of potency as such. For example, the bronze is potentially a statue, because it can take on the form of the statue. Thus, the melting down, the molding, and the finishing, which are all motions, are an actualization of the metal which is potentially a statue. Consequently, motion will be considered in all the categories in which potency is considered. And in those in which potency is not considered, motion will not be considered either. Thus motion is considered in the categories of substance, quantity, quality, and place. In substance there is generation and destruction; in quantity there is increase and decrease; in quality, alteration; and in place, motion in a circle, which is called ‘circular, and motion in straight line, which is called ‘direct. There are, moreover, six kinds of direct motion: upward, downward, inward, outward, motion to the right, and motion to the left. And so with circular motion there are seven kinds of motion with respect to place.

Now, everything that is changed is changed either in itself, or in something within itself, or in something around itself. If this is in the thing itself, it will constitute generation and destruction. If, however, it is in something in the thing itself, this will either be in quantity, in which case it will constitute increase and decrease, or it will be in quality, in which case it will constitute alteration. And if it is in something around the thing, then it will constitute change in place, because place is neither the thing itself which is moved, nor is it anything in it; rather, it accompanies the things moved and is round about them.

Generation differs from destruction. This is because generation is the passing from non-being to being, for that comes into being, or is generated, which was not before. But with destruction it is just the reverse, for destruction is the change from being to non-being. And increase differs from decrease, because increase is the motion to a greater quantity, whereas decrease is that to a lesser. And again, there are opposite passions in alteration, as heat is opposed to cold and black to white. Thus, while destruction is opposed to generation, and increase to decrease, to alteration are opposed the corresponding opposite and rest. For cooling is opposed to heating and so is rest, because, when the object being heated attains its highest temperature and reaches a limit, then it rests and ceases being heated. In the same way, both the contrary motion and rest are opposed to change in place. For here, while there are contraries, such as upward and downward, there is also rest. Thus, should one throw a lump of earth up into the air, it will not start its downward motion before it first comes to rest. There is, however, no contrary motion to that of the heavens.

Moreover, it seems that alteration accompanies the other kinds of motion. This is because the thing which is being generated and that which is being destroyed, the thing which is increasing and that which is decreasing, and that which is being moved with respect to place are all definitely being altered. Although with the natural motions we do find the motion of alteration accompanying the others, nevertheless it is possible for a thing to be altered without, however, its being moved with any other motion. A stone, for example, may be heated and cooled, but it will neither increase nor cease to be. And in the same way with the rest. So, even if alteration does accompany the other motions, it is possible for it to be considered in itself, and for that reason the distinction between it and the others has been conceded.

Now, Aristotle does not call change a motion. Thus in Book 5 of his Physics he has demonstrated that generation and destruction are changes, but not motions, because motion takes place while the thing moved remains intact. However, although we said that there were two contraries to alteration and to change in place, namely the opposite motion and rest, one should know that it is not impossible for two things to be contrary to one thing in different respects. Thus, rest is like habit and privation, whereas the opposite motion is contrary in the proper sense as cooling is to heating.

{Περὶ κινήσεως.} Κίνησίς ἐστιν ἐντελέχεια τοῦ δυνάμει, καθὸ τοιοῦτόν ἐστιν, οἷον ὁ χαλκὸς δυνάμει ἐστὶν ἀνδριάς: δύναται γὰρ ὁ χαλκὸς ἀπολαβεῖν τὸ εἶδος τοῦ ἀνδριάντος. Ἐντελέχεια οὖν ἐστι τοῦ χαλκοῦ τοῦ δυνάμει ὄντος ἀνδριάντος τὸ διαλύεσθαι, τὸ διαπλάττεσθαι, τὸ διαξέεσθαι, ἅπερ εἰσὶ κινήσεις. Ἐν ὅσαις οὖν κατηγορίαις θεωρεῖται τὸ δυνάμει, ἐν ταύταις θεωρηθήσεται ἡ κίνησις: ἐν ὅσαις δὲ οὐ θεωρεῖται τὸ δυνάμει, οὐδὲ ἡ κίνησις θεωρηθήσεται. Θεωρεῖται οὖν ἐν τῇ οὐσίᾳ, ἐν τῷ ποσῷ, ἐν τῷ ποιῷ, ἐν τῇ ποῦ κατηγορίᾳ. Ἐν μὲν τῇ οὐσίᾳ γένεσις καὶ φθορά, ἐν δὲ τῷ ποσῷ αὔξησις καὶ μείωσις, ἐν δὲ τῷ ποιῷ ἀλλοίωσις, ἐν δὲ τῇ ποῦ τὸ κύκλῳ φερόμενον, ὅπερ καλεῖται περιφορά, καὶ τὸ ἐπ' εὐθείας κινούμενον, ὅπερ λέγεται ἐπ' εὐθείας κίνησις. Τῆς δὲ ἐπ' εὐθείας κινήσεως διαφοραί εἰσιν ἕξ: τὸ ἄνω, τὸ κάτω, τὸ ἔσω, τὸ ἔξω, τὸ δεξιά, τὸ ἀριστερά. Διὸ μετὰ τῆς περιφορᾶς ἑπτὰ τοπικαὶ κινήσεις εἰσί: πᾶν γὰρ μεταβαλλόμενον ἢ καθ' αὑτὸ μεταβάλλεται ἢ κατά τι τῶν ἐν αὐτῷ ἢ κατά τι τῶν περὶ αὐτό: καὶ εἰ μὲν καθ' αὑτό, ποιεῖ γένεσιν καὶ φθοράν: εἰ δὲ κατά τι τῶν ἐν αὐτῷ ἢ κατὰ τὸ ποσόν, καὶ ποιεῖ αὔξησιν καὶ μείωσιν, ἢ κατὰ τὸ ποιόν, καὶ ποιεῖ ἀλλοίωσιν: εἰ δὲ κατὰ τὸ περὶ αὐτό, ποιεῖ τὴν κατὰ τόπον μεταβολήν: ὁ γὰρ τόπος οὔτε αὐτό ἐστι κινούμενον οὔτε τι τῶν ἐν αὐτῷ, ἀλλὰ τοῖς κινουμένοις παρέπεται καὶ περὶ τὰ κινούμενά ἐστι. Διαφέρει δὲ γένεσις καὶ φθορά: γένεσις μὲν γάρ ἐστιν ἡ ἀπὸ τοῦ μὴ ὄντος εἰς τὸ εἶναι πρόοδος: ὅπερ γὰρ οὐκ ἦν πρότερον, τοῦτο γίνεται. Ἡ δὲ φθορὰ τὸ ἀνάπαλιν ἀπὸ τοῦ ὄντος ἐπὶ τὸ μὴ εἶναι μεταβολή. _ αὔξησις δὲ καὶ μείωσις: αὔξησις μὲν γάρ ἐστιν ἡ ἐπὶ τὸ μεῖζον κίνησις: μείωσις δὲ ἡ ἐπὶ τὸ ἔλαττον. _ἐν δὲ τῇ ἀλλοιώσει πάλιν τὰ ἀντικείμενα πάθη, θερμότης ψύξει, τῷ λευκῷ τὸ μέλαν. Ἀντίκειται τοίνυν τῇ μὲν γενέσει φθορά, τῇ δὲ αὐξήσει μείωσις, τῇ δὲ ἀλλοιώσει τὸ ἀντικείμενον καὶ ἡ ἠρεμία. Ἀντικείμενον μὲν θερμάνσει ψύξις ἠρεμία τε: ὅταν γὰρ λάβῃ πέρας τὸ θερμαινόμενον καὶ ἔλθῃ ἐπὶ τὴν ἄκραν θερμότητα, ἠρεμεῖ καὶ παύεται τοῦ θερμαίνεσθαι. Οὕτω καὶ τῇ κατὰ τόπον μεταβολῇ καὶ ἡ ἐναντία κίνησις ἀντίκειται καὶ ἡ ἠρεμία, ἐναντία μέν, ὡς ἡ ἄνω κίνησις τῇ κάτω ἠρεμίᾳ τε: ἐὰν γὰρ βῶλον ῥίψῃ τις ἐπὶ τὰ ἄνω, οὐ πρότερον ἐπὶ τὰ κάτω κινηθήσεται, πρὶν ἠρεμία τις γένηται. Τῇ δὲ οὐρανίᾳ κινήσει οὐκ ἔστιν ἐναντία κίνησις. Δοκεῖ δὲ ἡ ἀλλοίωσις παρέπεσθαι ταῖς λοιπαῖς κινήσεσι: καὶ γὰρ καὶ τὸ γινόμενον καὶ τὸ φθειρόμενον καὶ τὸ αὐξάνον καὶ τὸ μειούμενον καὶ τὸ κινούμενον κατὰ τόπον πάντως ἀλλοιοῦται. Ἐπὶ δὲ τῶν φυσικῶν κινήσεων, εἰ καὶ εὑρίσκομεν παρεπομένην τὴν ἀλλοίωσιν ταῖς λοιπαῖς κινήσεσιν, ὅμως ἐνδέχεται ἀλλοιοῦσθαι μέν, μὴ μέντοι δὲ κινεῖσθαι καθ' ἑτέραν κίνησιν, ὡς ἐπὶ λίθου: οὗτος γὰρ θερμαίνεται καὶ ψύχεται καὶ οὔτε αὔξει οὔτε γίνεται: καὶ ἐπὶ τῶν λοιπῶν ὁμοίως. Ὥστε εἰ καὶ παρέπεται ἀλλοίωσις ταῖς λοιπαῖς κινήσεσιν, ὅμως ἐνδέχεται καθ' αὑτὴν θεωρεῖσθαι: ὅθεν ὁμολογεῖται αὐτῶν τὸ διάφορον. Κίνησιν δὲ λέγει Ἀριστοτέλης τὴν μεταβολήν. Ἐν γὰρ τῷ πέμπτῳ λόγῳ τῆς Φυσικῆς ἀκροάσεως ἀπέδειξεν, ὅτι γένεσις καὶ φθορὰ μεταβολαὶ μέν εἰσι, κινήσεις δὲ οὔκ εἰσι, διότι ἡ κίνησις σῳζομένου τοῦ πράγματος γίνεται. Εἰ δὲ καὶ τῇ ἀλλοιώσει καὶ τῇ κατὰ τόπον μεταβολῇ ἔφημεν δύο ἐναντία εἶναι, τήν τε κίνησιν καὶ τὴν ἠρεμίαν, ἰστέον, ὡς οὐκ ἀδύνατον κατ' ἄλλο καὶ ἄλλο δύο ἑνὶ εἶναι ἐναντία: ἠρεμία μὲν γὰρ ὡς λῆξις καὶ στέρησις, ἡ δὲ ἀντικειμένη κυρίως ὡς θερμάνσει ψύξις.