§9.4εἰ δέ ἐστι τὸ εἰρημένον τὸ δυνατὸν ἢ ἀκολουθεῖ, φανερὸν ὅτι οὐκ ἐνδέχεται ἀληθὲς εἶναι τὸ εἰπεῖν ὅτι δυνατὸν μὲν τοδί, οὐκ ἔσται δέ, ὥστε τὰ ἀδύνατα εἶναι ταύτῃ διαφεύγειν· λέγω δὲ οἷον εἴ τις φαίη δυνατὸν τὴν διάμετρον μετρηθῆναι οὐ μέντοι μετρηθήσεσθαι—ὁ μὴ λογιζόμενος τὸ ἀδύνατον εἶναι—ὅτι οὐθὲν κωλύει δυνατόν τι ὂν εἶναι ἢ γενέσθαι μὴ εἶναι μηδʼ ἔσεσθαι.
If what has been said is the capable (possible) or follows from it, it is clear that it cannot be true to say that 'this is possible, but it will not be', so that the impossible things would escape us in this way; I mean, for example, if someone were to say that the diagonal is capable of being measured but will not be measured — not taking into account the impossible — because nothing prevents something which is capable of being or becoming from not being or not about to be.
ἀλλʼ ἐκεῖνο ἀνάγκη ἐκ τῶν κειμένων, εἰ καὶ ὑποθοίμεθα εἶναι ἢ γεγονέναι ὃ οὐκ ἔστι μὲν δυνατὸν δέ, ὅτι οὐθὲν ἔσται ἀδύνατον·
But this is necessary from the assumptions, that if we should suppose to be or to have happened that which is not indeed but is possible, nothing impossible will follow.
συμβήσεται δέ γε, τὸ γὰρ μετρεῖσθαι ἀδύνατον.
But it will indeed follow, for being measured is impossible.
οὐ γὰρ δή ἐστι ταὐτὸ τὸ ψεῦδος καὶ τὸ ἀδύνατον· τὸ γάρ σε ἑστάναι νῦν ψεῦδος μέν, οὐκ ἀδύνατον δέ.
For indeed, the false and the impossible are not the same; for that you are standing now is false, but not impossible.
ἅμα δὲ δῆλον καὶ ὅτι, εἰ τοῦ Α ὄντος ἀνάγκη τὸ Β εἶναι, καὶ δυνατοῦ ὄντος εἶναι τοῦ Α καὶ τὸ Β ἀνάγκη εἶναι δυνατόν·
At the same time it is also clear that, if B is necessary when A exists, then also B must be possible when A is possible.
εἰ γὰρ μὴ ἀνάγκη δυνατὸν εἶναι, οὐθὲν κωλύει μὴ εἶναι δυνατὸν εἶναι.
For if it is not necessary for B to be possible, nothing prevents B from not being possible.
ἔστω δὴ τὸ Α δυνατόν.
Let A be possible.
οὐκοῦν ὅτε τὸ Α δυνατὸν εἴη εἶναι, εἰ τεθείη τὸ Α, οὐθὲν ἀδύνατον εἶναι συνέβαινεν·
Therefore, when A is possible to be, if A were assumed to be, nothing impossible followed.
τὸ δέ γε Β ἀνάγκη εἶναι.
But B is necessary to be.
ἀλλʼ ἦν ἀδύνατον.
But [suppose] B was impossible.
ἔστω δὴ ἀδύνατον.
Let it be impossible.
εἰ δὴ ἀδύνατον εἶναι τὸ Β, ἀνάγκη καὶ τὸ Α εἶναι.
If, then, B is impossible to be, A too must be [impossible].
ἀλλʼ ἦν ἄρα τὸ πρῶτον ἀδύνατον· καὶ τὸ δεύτερον ἄρα.
But the first [A being impossible] was impossible; therefore the second [B being impossible] also is impossible.
ἂν ἄρα ᾖ τὸ Α δυνατόν, καὶ τὸ Β ἔσται δυνατόν, εἴπερ οὕτως εἶχον ὥστε τοῦ Α ὄντος ἀνάγκη εἶναι τὸ Β. ἐὰν δὴ οὕτως ἐχόντων τῶν Α Β μὴ ᾖ δυνατὸν τὸ Β οὕτως, οὐδὲ τὰ Α Β ἕξει ὡς ἐτέθη·
If, then, A is possible, B also will be possible, if indeed they were so related that when A exists, B is necessarily to exist. If, then, A and B being so related, B is not possible in this way, neither will A and B be related as they were assumed.
καὶ εἰ τοῦ Α δυνατοῦ ὄντος ἀνάγκη τὸ Β δυνατὸν εἶναι, εἰ ἔστι τὸ Α ἀνάγκη εἶναι καὶ τὸ Β. τὸ γὰρ δυνατὸν εἶναι ἐξ ἀνάγκης τὸ Β εἶναι, εἰ τὸ Α δυνατόν, τοῦτο σημαίνει, ἐὰν ᾖ τὸ Α καὶ ὅτε καὶ ὡς ἦν δυνατὸν εἶναι, κἀκεῖνο τότε καὶ οὕτως εἶναι ἀναγκαῖον.
And if when A is possible, B is necessarily possible, if A exists, B also must exist. For that 'B is necessarily possible, if A is possible' means this: if A exists, both when and as it was possible to exist, that [B] also then and in that way is necessary to exist.
§9.5ἁπασῶν δὲ τῶν δυνάμεων οὐσῶν τῶν μὲν συγγενῶν οἷον τῶν αἰσθήσεων, τῶν δὲ ἔθει οἷον τῆς τοῦ αὐλεῖν, τῶν δὲ μαθήσει οἷον τῆς τῶν τεχνῶν, τὰς μὲν ἀνάγκη προενεργήσαντας ἔχειν, ὅσαι ἔθει καὶ λόγῳ, τὰς δὲ μὴ τοιαύτας καὶ τὰς ἐπὶ τοῦ πάσχειν οὐκ ἀνάγκη.
Of all the potentialities, some being innate, like the senses, some by habit, like that of flute-playing, and some by learning, like that of the arts, those which are by habit and reason we must acquire by having previously active, but those which are not of this kind and those of being acted upon we need not.
ἐπεὶ δὲ τὸ δυνατὸν τὶ δυνατὸν καὶ ποτὲ καὶ πὼς καὶ ὅσα ἄλλα ἀνάγκη προσεῖναι ἐν τῷ διορισμῷ, καὶ τὰ μὲν κατὰ λόγον δύναται κινεῖν καὶ αἱ δυνάμεις αὐτῶν μετὰ λόγου, τὰ δὲ ἄλογα καὶ αἱ δυνάμεις ἄλογοι, κἀκείνας μὲν ἀνάγκη ἐν ἐμψύχῳ εἶναι ταύτας δὲ ἐν ἀμφοῖν, τὰς μὲν τοιαύτας δυνάμεις ἀνάγκη, ὅταν ὡς δύνανται τὸ ποιητικὸν καὶ τὸ παθητικὸν πλησιάζωσι, τὸ μὲν ποιεῖν τὸ δὲ πάσχειν, ἐκείνας δʼ οὐκ ἀνάγκη· αὗται μὲν γὰρ πᾶσαι μία ἑνὸς ποιητική, ἐκεῖναι δὲ τῶν ἐναντίων, ὥστε ἅμα ποιήσει τὰ ἐναντία· τοῦτο δὲ ἀδύνατον.
Since that which is capable is capable of something, and at some time, and in some way, and with all other things which must be added in the definition, and some can produce motion according to reason and their potentialities are with reason, and others are irrational and their potentialities irrational, and the former must be in a living thing, but the latter in both, for such [irrational] potentialities it is necessary, when the active and the passive approach as they are capable, the one to act and the other to be acted upon, but for the former [rational] it is not necessary; for all these [irrational] are productive of one effect, but the former [rational] of contrary effects, so that they would produce contraries at the same time; but this is impossible.
ἀνάγκη ἄρα ἕτερόν τι εἶναι τὸ κύριον· λέγω δὲ τοῦτο ὄρεξιν ἢ προαίρεσιν.
There must, then, be something else which is decisive; I mean by this desire (orexis) or choice (proairesis).
ὁποτέρου γὰρ ἂν ὀρέγηται κυρίως, τοῦτο ποιήσει ὅταν ὡς δύναται ὑπάρχῃ καὶ πλησιάζῃ τῷ παθητικῷ· ὥστε τὸ δυνατὸν κατὰ λόγον ἅπαν ἀνάγκη, ὅταν ὀρέγηται οὗ ἔχει τὴν δύναμιν καὶ ὡς ἔχει, τοῦτο ποιεῖν· ἔχει δὲ παρόντος τοῦ παθητικοῦ καὶ ὡδὶ ἔχοντος· εἰ δὲ μή, ποιεῖν οὐ δυνήσεται (τὸ γὰρ μηθενὸς τῶν ἔξω κωλύοντος προσδιορίζεσθαι οὐθὲν ἔτι δεῖ· τὴν γὰρ δύναμιν ἔχει ὡς ἔστι δύναμις τοῦ ποιεῖν, ἔστι δʼ οὐ πάντως ἀλλʼ ἐχόντων πῶς, ἐν οἷς ἀφορισθήσεται καὶ τὰ ἔξω κωλύοντα· ἀφαιρεῖται γὰρ ταῦτα τῶν ἐν τῷ διορισμῷ προσόντων ἔνια)· διὸ οὐδʼ ἐὰν ἅμα βούληται ἢ ἐπιθυμῇ ποιεῖν δύο ἢ τὰ ἐναντία, οὐ ποιήσει· οὐ γὰρ οὕτως ἔχει αὐτῶν τὴν δύναμιν οὐδʼ ἔστι τοῦ ἅμα ποιεῖν ἡ δύναμις, ἐπεὶ ὧν ἐστὶν οὕτως ποιήσει.
For whichever of the two it decisively desires, this it will do when it exists in the way it is capable and approaches the passive; so that everything capable according to reason must do this, when it desires that of which it has the potentiality and in the way it has it; and it has the potentiality when the passive is present and is in such a state; otherwise it will not be able to act. (For there is no longer any need to add the specification 'if nothing external prevents'; for it has the potentiality in so far as it is the potentiality of acting, and this is not in every way but when things are in a certain state, in which also external obstacles will be defined as excluded; for these [external obstacles] are removed by some of the things present in the definition); therefore even if it should wish or desire to do two or contrary things at the same time, it will not do them; for it does not have the potentiality for them in this way, nor is there a potentiality of doing them at the same time, since it will do those of which it has the potentiality in the way it has it.