METAPHYSICS
BOOK IX

ARISTOTLE’S TEXT Chapter 1: 1045b 27-1046a 35
[1045β] [27] περὶ μὲν οὖν τοῦ πρώτως ὄντος καὶ πρὸς ὃ πᾶσαι αἱ ἄλλαι κατηγορίαι τοῦ ὄντος ἀναφέρονται εἴρηται, περὶ τῆς οὐσίας (κατὰ γὰρ τὸν τῆς οὐσίας λόγον λέγεται τἆλλα [30] ὄντα, τό τε ποσὸν καὶ τὸ ποιὸν καὶ τἆλλα τὰ οὕτω λεγόμενα: πάντα γὰρ ἕξει τὸν τῆς οὐσίας λόγον, ὥσπερ εἴπομεν ἐν τοῖς πρώτοις λόγοις): ἐπεὶ δὲ λέγεται τὸ ὂν τὸ μὲν τὸ τὶ ἢ ποιὸν ἢ ποσόν, τὸ δὲ κατὰ δύναμιν καὶ ἐντελέχειαν καὶ κατὰ τὸ ἔργον, διορίσωμεν καὶ περὶ δυνάμεως [35] καὶ ἐντελεχείας, καὶ πρῶτον περὶ δυνάμεως ἣ λέγεται μὲν μάλιστα κυρίως, οὐ μὴν χρησιμωτάτη γέ ἐστι πρὸς ὃ βουλόμεθα νῦν: [1046α] [1] ἐπὶ πλέον γάρ ἐστιν ἡ δύναμις καὶ ἡ ἐνέργεια τῶν μόνον λεγομένων κατὰ κίνησιν.	742. We have dealt then with the primary kind of being and the one to which all the other categories of being are referred, namely, substance. For it is in reference to the concept of substance that the other categories are called beings, i.e., quantity, quality, and others which are spoken of in this way; for all involve the concept of substance, as we have stated in our first discussions (562). And since being is used in one sense of quiddity or quantity or quality, and in another sense of potency and actuality and activity, let us now establish the truth about potency and actuality. And first let us consider potency in the most proper sense of the term, although not the one most useful for our present purpose; for potency and actuality are found in more things than those which are referred merely to motion. But when we have spoken about this sense of potency we shall, in our discussions about actuality, also explain the other senses of potency.
ἀλλ᾽ εἰπόντες περὶ ταύτης, ἐν τοῖς περὶ τῆς ἐνεργείας διορισμοῖς δηλώσομεν καὶ περὶ τῶν ἄλλων. ὅτι μὲν οὖν λέγεται [5] πολλαχῶς ἡ δύναμις καὶ τὸ δύνασθαι, διώρισται ἡμῖν ἐν ἄλλοις: τούτων δ᾽ ὅσαι μὲν ὁμωνύμως λέγονται δυνάμεις ἀφείσθωσαν (ἔνιαι γὰρ ὁμοιότητί τινι λέγονται, καθάπερ ἐν γεωμετρίᾳ καὶ δυνατὰ καὶ ἀδύνατα λέγομεν τῷ εἶναί πως ἢ μὴ εἶναι), ὅσαι δὲ πρὸς τὸ αὐτὸ εἶδος, πᾶσαι ἀρχαί [10] τινές εἰσι, καὶ πρὸς πρώτην μίαν λέγονται, ἥ ἐστιν ἀρχὴ μεταβολῆς ἐν ἄλλῳ ἢ ᾗ ἄλλο. ἡ μὲν γὰρ τοῦ παθεῖν ἐστὶ δύναμις, ἡ ἐν αὐτῷ τῷ πάσχοντι ἀρχὴ μεταβολῆς παθητικῆς ὑπ᾽ ἄλλου ἢ ᾗ ἄλλο: ἡ δ᾽ ἕξις ἀπαθείας τῆς ἐπὶ τὸ χεῖρον καὶ φθορᾶς τῆς ὑπ᾽ ἄλλου ἢ ᾗ ἄλλο ὑπ᾽ ἀρχῆς [15] μεταβλητικῆς. ἐν γὰρ τούτοις ἔνεστι πᾶσι τοῖς ὅροις ὁ τῆς πρώτης δυνάμεως λόγος. πάλιν δ᾽ αὗται δυνάμεις λέγονται ἢ τοῦ μόνον ποιῆσαι ἢ [τοῦ] παθεῖν ἢ τοῦ καλῶς, ὥστε καὶ ἐν τοῖς τούτων λόγοις ἐνυπάρχουσί πως οἱ τῶν προτέρων δυνάμεων λόγοι.	743. That the terms potency and can are used in many senses we have made evident elsewhere (467). And all of those senses of potency which are equivocal may be dismissed; for some senses of potency [or power] are merely figurative, as in geometry. And we say that things are possible or impossible because they either are or are not in some particular way. But all those potencies belonging to the same species are principles and are referred to one primary kind of potency, which is the principle of change in some other thing inasmuch as it is other. For one kind is a potency for being acted upon, which is in the patient and is the principle of its being passively moved by another inasmuch as it is other; and another kind of potency is the state of insusceptibility to change for the worse and to corruption by some other thing inasmuch as it is other, i.e., by a principle of change. And the intelligible character of the primary kind of potency is found in all of these terms. Again, these potencies are said to be potencies either just for acting or for being acted upon, or for acting or being acted upon well, so that in these latter kinds of potencies the notes of the prior kind are somehow present.
φανερὸν οὖν ὅτι ἔστι μὲν ὡς μία δύναμις [20] τοῦ ποιεῖν καὶ πάσχειν (δυνατὸν γάρ ἐστι καὶ τῷ ἔχειν αὐτὸ δύναμιν τοῦ παθεῖν καὶ τῷ ἄλλο ὑπ᾽ αὐτοῦ), ἔστι δὲ ὡς ἄλλη. ἡ μὲν γὰρ ἐν τῷ πάσχοντι (διὰ γὰρ τὸ ἔχειν τινὰ ἀρχήν, καὶ εἶναι καὶ τὴν ὕλην ἀρχήν τινα, πάσχει τὸ πάσχον, καὶ ἄλλο ὑπ᾽ ἄλλου: τὸ λιπαρὸν μὲν [25] γὰρ καυστὸν τὸ δ᾽ ὑπεῖκον ὡδὶ θλαστόν, ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων), ἡ δ᾽ ἐν τῷ ποιοῦντι, οἷον τὸ θερμὸν καὶ ἡ οἰκοδομική, ἡ μὲν ἐν τῷ θερμαντικῷ ἡ δ᾽ ἐν τῷ οἰκοδομικῷ: διὸ ᾗ συμπέφυκεν, οὐθὲν πάσχει αὐτὸ ὑφ᾽ ἑαυτοῦ: ἓν γὰρ καὶ οὐκ ἄλλο.	744. It is evident, then, that in one sense the potency for acting and for being acted upon are one; for a thing is potential both because it itself has the potency for being acted upon, and because something else can be acted upon by it. And in another sense these potencies are different; for the one is in the patient, since it is because it has a principle, and because matter is a principle, that the patient is acted upon and changed by something else. For what is oily is capable of being burnt, and what is yielding in some way is capable of being broken (and the supposit is capable of being expressed);’ and the same is true in other cases. And another kind of potency is in the agent, as the potency to heat and the potency to build-the former in the thing capable of heating, and the latter in the person capable of building. Hence, inasmuch as a thing is by nature a unity, it cannot be acted upon by itself; for it is one thing and not also something else.
καὶ ἡ ἀδυναμία καὶ τὸ ἀδύνατον [30] ἡ τῇ τοιαύτῃ δυνάμει ἐναντία στέρησίς ἐστιν, ὥστε τοῦ αὐτοῦ καὶ κατὰ τὸ αὐτὸ πᾶσα δύναμις ἀδυναμίᾳ. ἡ δὲ στέρησις λέγεται πολλαχῶς: καὶ γὰρ τὸ μὴ ἔχον καὶ τὸ πεφυκὸς ἂν μὴ ἔχῃ, ἢ ὅλως ἢ ὅτε πέφυκεν, καὶ ἢ ὡδί, οἷον παντελῶς, ἢ κἂν ὁπωσοῦν. ἐπ᾽ ἐνίων δέ, ἂν πεφυκότα [35] ἔχειν μὴ ἔχῃ βίᾳ, ἐστερῆσθαι ταῦτα λέγομεν.	745. And incapacity or impossibility is the privation contrary to such potency, so that every potency and incapacity belong to the same subject and refer to the same attribute. And there are various kinds of privation; for there is one kind of privation when a thing does not have some attribute which it is naturally disposed to have, either in general, or when it is naturally disposed to have it. And this is so either in a particular way, for example, completely, or even in any way at all. And in some cases if things are naturally disposed to have some attribute and do not have it as a result of force, we say that they are deprived of it.

ARISTOTLE’S TEXT Chapter 2:1046a 36-1046b 28
ἐπεὶ δ᾽ αἱ μὲν ἐν τοῖς ἀψύχοις ἐνυπάρχουσιν ἀρχαὶ τοιαῦται, αἱ δ᾽ ἐν τοῖς ἐμψύχοις καὶ ἐν ψυχῇ καὶ τῆς ψυχῆς ἐν τῷ λόγον ἔχοντι, [1046β] [1] δῆλον ὅτι καὶ τῶν δυνάμεων αἱ μὲν ἔσονται ἄλογοι αἱ δὲ μετὰ λόγου: διὸ πᾶσαι αἱ τέχναι καὶ αἱ ποιητικαὶ ἐπιστῆμαι δυνάμεις εἰσίν: ἀρχαὶ γὰρ μεταβλητικαί εἰσιν ἐν ἄλλῳ ἢ ᾗ ἄλλο.	746. And since some such principles are present in non-living things, and others in living things and in the soul, and in the soul having reason, it is evident that some potencies will be devoid of reason and others will be rational. And for this reason all the arts and productive sciences are potencies; for they are principles of change in some other thing inasmuch as it is other.
καὶ αἱ μὲν [5] μετὰ λόγου πᾶσαι τῶν ἐναντίων αἱ αὐταί, αἱ δὲ ἄλογοι μία ἑνός, οἷον τὸ θερμὸν τοῦ θερμαίνειν μόνον᾽ ἡ δὲ ἰατρικὴ νόσου καὶ ὑγιείας.	747. And all those potencies which are rational are open to contrary determinations, and those which are irrational are each determined to one thing; for example, what is hot is capable of heating, whereas the medical art is concerned with both sickness and health.
αἴτιον δὲ ὅτι λόγος ἐστὶν ἡ ἐπιστήμη, ὁ δὲ λόγος ὁ αὐτὸς δηλοῖ τὸ πρᾶγμα καὶ τὴν στέρησιν, πλὴν οὐχ ὡσαύτως, καὶ ἔστιν ὡς ἀμφοῖν ἔστι δ᾽ ὡς [10] τοῦ ὑπάρχοντος μᾶλλον, ὥστ᾽ ἀνάγκη καὶ τὰς τοιαύτας ἐπιστήμας εἶναι μὲν τῶν ἐναντίων, εἶναι δὲ τοῦ μὲν καθ᾽ αὑτὰς τοῦ δὲ μὴ καθ᾽ αὑτάς: καὶ γὰρ ὁ λόγος τοῦ μὲν καθ᾽ αὑτὸ τοῦ δὲ τρόπον τινὰ κατὰ συμβεβηκός: ἀποφάσει γὰρ καὶ ἀποφορᾷ δηλοῖ τὸ ἐναντίον: ἡ γὰρ στέρησις [15] ἡ πρώτη τὸ ἐναντίον, αὕτη δὲ ἀποφορὰ θατέρου.	748. And the reason of this is that science is a conception [or rational plan], and the same conception explains both a thing and its privation, though not in the same way. And in one sense it is a conception of both, and in another it applies rather to the existent thing. Hence it is necessary that such sciences should deal with contraries, but with one directly and with the other indirectly; for the conception applies to one essentially, but to the other in a kind of accidental way, because it explains the contrary by negation and removal. For the contrary is the primary privation, and this is the removal of the other term.
ἐπεὶ δὲ τὰ ἐναντία οὐκ ἐγγίγνεται ἐν τῷ αὐτῷ, ἡ δ᾽ ἐπιστήμη δύναμις τῷ λόγον ἔχειν, καὶ ἡ ψυχὴ κινήσεως ἔχει ἀρχήν, τὸ μὲν ὑγιεινὸν ὑγίειαν μόνον ποιεῖ καὶ τὸ θερμαντικὸν θερμότητα καὶ τὸ ψυκτικὸν ψυχρότητα, ὁ δ᾽ ἐπιστήμων [20] ἄμφω. λόγος γάρ ἐστιν ἀμφοῖν μέν, οὐχ ὁμοίως δέ, καὶ ἐν ψυχῇ ἣ ἔχει κινήσεως ἀρχήν: ὥστε ἄμφω ἀπὸ τῆς αὐτῆς ἀρχῆς κινήσει πρὸς ταὐτὸ συνάψασα: διὸ τὰ κατὰ λόγον δυνατὰ τοῖς ἄνευ λόγου δυνατοῖς ποιεῖ τἀναντία: μιᾷ γὰρ ἀρχῇ περιέχεται, τῷ λόγῳ.	749. Moreover, since contraries do not exist in the same subject, and since a science is a potency in a being which possesses a rational plan, and the soul has a principle of motion, it follows that, while what is healthful produces only health, and what is capable of heating produces only heat, and what is capable of cooling produces only cold, one who has a science may be occupied with both contraries. For reason extends to both but not in the same manner, and it exists in a soul which possesses a principle of motion Hence the soul will initiate both by the same principle by joining both to the same rational plan. And for this reason those things whose potency is rational produce effects contrary to those whose potency is irrational; for one principle of contrary determinations is contained in the rational plan.
φανερὸν δὲ καὶ ὅτι [25] τῇ μὲν τοῦ εὖ δυνάμει ἀκολουθεῖ ἡ τοῦ μόνον ποιῆσαι ἢ παθεῖν δύναμις, ταύτῃ δ᾽ ἐκείνη οὐκ ἀεί: ἀνάγκη γὰρ τὸν εὖ ποιοῦντα καὶ ποιεῖν, τὸν δὲ μόνον ποιοῦντα οὐκ ἀνάγκη καὶ εὖ ποιεῖν.	750. It is also evident that a potency for doing something well involves the potency of merely doing something or undergoing some change. But the latter does not always involve the former; for he who does a thing well must do it, but he who does something need not do it well.

ARISTOTLE’S TEXT Chapters 3 & 4: 1046b 29-1047b 30
εἰσὶ δέ τινες οἵ φασιν, οἷον οἱ Μεγαρικοί, ὅταν ἐνεργῇ [30] μόνον δύνασθαι, ὅταν δὲ μὴ ἐνεργῇ οὐ δύνασθαι, οἷον τὸν [31] μὴ οἰκοδομοῦντα οὐ δύνασθαι οἰκοδομεῖν, ἀλλὰ τὸν οἰκοδομοῦντα ὅταν οἰκοδομῇ: ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων.	751. There are some, such as the members of the Megaric school, who say that a thing has a potency for acting only when it is acting, and that when it is not acting it does not have this potency; for example, one who is not building does not have the power of building, but only one who is building when he is building; and it is the same in other cases.
οἷς τὰ συμβαίνοντα ἄτοπα οὐ χαλεπὸν ἰδεῖν. δῆλον γὰρ ὅτι οὔτ᾽ οἰκοδόμος ἔσται ἐὰν μὴ οἰκοδομῇ (τὸ γὰρ οἰκοδόμῳ [35] εἶναι τὸ δυνατῷ εἶναί ἐστιν οἰκοδομεῖν), ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων τεχνῶν. εἰ οὖν ἀδύνατον τὰς τοιαύτας ἔχειν τέχνας μὴ μαθόντα ποτὲ καὶ λαβόντα, [1047α] [1] καὶ μὴ ἔχειν μὴ ἀποβαλόντα ποτέ (ἢ γὰρ λήθῃ ἢ πάθει τινὶ ἢ χρόνῳ: οὐ γὰρ δὴ τοῦ γε πράγματος φθαρέντος, ἀεὶ γὰρ ἔστιν), ὅταν παύσηται, οὐχ ἕξει τὴν τέχνην, πάλιν δ᾽ εὐθὺς οἰκοδομήσει πῶς λαβών;	752. It is not difficult to see the absurd consequences of this position. For it is evident, according to this view, that a man will not be a builder if he is not building, because to be a builder is to be able to build. The same is true in the case of the other arts. Therefore, if it is impossible to have such arts unless one has at some time learnt and acquired them, and if it is impossible not to have them unless one has at some time lost them (either through forgetfulness or through some change or through the passage of time; for this cannot occur as a result of the object being destroyed, since it always exists), when one will have ceased to use an art he will not have it; and yet he will be able to build forthwith, thus somehow getting it back again.
καὶ τὰ ἄψυχα δὴ ὁμοίως: οὔτε γὰρ [5] ψυχρὸν οὔτε θερμὸν οὔτε γλυκὺ οὔτε ὅλως αἰσθητὸν οὐθὲν ἔσται μὴ αἰσθανομένων: ὥστε τὸν Πρωταγόρου λόγον συμβήσεται λέγειν αὐτοῖς.	753. And the same thing will be true in the case of non-living things; for neither the cold nor the hot nor the sweet nor the bitter nor any sensible thing will exist in any way at all if they are not being sensed. Hence they will have to maintain the theory that Protagoras did.
ἀλλὰ μὴν οὐδ᾽ αἴσθησιν ἕξει οὐδὲν ἂν μὴ αἰσθάνηται μηδ᾽ ἐνεργῇ. εἰ οὖν τυφλὸν τὸ μὴ ἔχον ὄψιν, πεφυκὸς δὲ καὶ ὅτε πέφυκε καὶ ἔτι ὄν, οἱ αὐτοὶ [10] τυφλοὶ ἔσονται πολλάκις τῆς ἡμέρας, καὶ κωφοί.	754. In fact nothing will have senses unless it is sensing or acting. Therefore, if that is blind which does not have the power of sight, though it is designed by nature to have it, and when it is designed by nature to have it, and so long as it exists, the same persons will be blind many times during the day; and deaf as well.
ἔτι εἰ ἀδύνατον τὸ ἐστερημένον δυνάμεως, τὸ μὴ γιγνόμενον ἀδύνατον ἔσται γενέσθαι: τὸ δ᾽ ἀδύνατον γενέσθαι ὁ λέγων ἢ εἶναι ἢ ἔσεσθαι ψεύσεται (τὸ γὰρ ἀδύνατον τοῦτο ἐσήμαινεν), ὥστε οὗτοι οἱ λόγοι ἐξαιροῦσι καὶ κίνησιν καὶ γένεσιν. [15] ἀεὶ γὰρ τό τε ἑστηκὸς ἑστήξεται καὶ τὸ καθήμενον καθεδεῖται: οὐ γὰρ ἀναστήσεται ἂν καθέζηται: ἀδύνατον γὰρ ἔσται ἀναστῆναι ὅ γε μὴ δύναται ἀναστῆναι.	755. Further, if what is deprived of a potency is incapable, it will be impossible for that to come into being which has not yet been generated; but he who says that what cannot possibly be generated either is or will be, is in error; for this is what impossible or incapable means. Hence these theories do away with both motion and generation; for what is standing will always stand, and what is sitting will always sit, because if it is sitting it will not get up, since it is impossible for anything to get up which has no possibility of doing so.
εἰ οὖν μὴ ἐνδέχεται ταῦτα λέγειν, φανερὸν ὅτι δύναμις καὶ ἐνέργεια ἕτερόν ἐστιν (ἐκεῖνοι δ᾽ οἱ λόγοι δύναμιν καὶ ἐνέργειαν ταὐτὸ [20] ποιοῦσιν, διὸ καὶ οὐ μικρόν τι ζητοῦσιν ἀναιρεῖν), ὥστε ἐνδέχεται δυνατὸν μέν τι εἶναι μὴ εἶναι δέ, καὶ δυνατὸν μὴ εἶναι εἶναι δέ, ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων κατηγοριῶν δυνατὸν βαδίζειν ὂν μὴ βαδίζειν, καὶ μὴ βαδίζειν δυνατὸν ὂν βαδίζειν.	756. Therefore, if it is impossible to maintain this, it is evident that potency and actuality are distinct. But these views make potency and actuality the same, and for this reason it is no small thing which they seek to destroy. Hence it is possible for a thing to be capable of being and yet not be, and for a thing not to be and yet be capable of being. And it is similar in the case of the other categories; for example, a thing may be capable of walking and yet not walk, and be capable of not walking and yet walk.
ἔστι δὲ δυνατὸν τοῦτο ᾧ ἐὰν ὑπάρξῃ [25] ἡ ἐνέργεια οὗ λέγεται ἔχειν τὴν δύναμιν, οὐθὲν ἔσται ἀδύνατον. λέγω δὲ οἷον, εἰ δυνατὸν καθῆσθαι καὶ ἐνδέχεται καθῆσθαι, τούτῳ ἐὰν ὑπάρξῃ τὸ καθῆσθαι, οὐδὲν ἔσται ἀδύνατον: καὶ εἰ κινηθῆναι ἢ κινῆσαι ἢ στῆναι ἢ στῆσαι ἢ εἶναι ἢ γίγνεσθαι ἢ μὴ εἶναι ἢ μὴ γίγνεσθαι, ὁμοίως.	757. Moreover, a thing has a potency if there is nothing impossible in its having the actuality of that of which it is said to have the potency. I mean, for example, that if a thing is capable of sitting, and it turns out to be sitting, there will be nothing impossible in its having a sitting position; and it is similar if it is capable of being moved or of moving something, or of standing or causing a thing to stand, or of being or coming to be, or of not being or not coming to be.
[30] ἐλήλυθε δ᾽ ἡ ἐνέργεια τοὔνομα, ἡ πρὸς τὴν ἐντελέχειαν συντιθεμένη, καὶ ἐπὶ τὰ ἄλλα ἐκ τῶν κινήσεων μάλιστα: δοκεῖ γὰρ ἡ ἐνέργεια μάλιστα ἡ κίνησις εἶναι, διὸ καὶ τοῖς μὴ οὖσιν οὐκ ἀποδιδόασι τὸ κινεῖσθαι, ἄλλας δέ τινας κατηγορίας, οἷον διανοητὰ καὶ ἐπιθυμητὰ εἶναι τὰ μὴ ὄντα, [35] κινούμενα δὲ οὔ, τοῦτο δὲ ὅτι οὐκ ὄντα ἐνεργείᾳ ἔσονται ἐνεργείᾳ. [1047β] [1] τῶν γὰρ μὴ ὄντων ἔνια δυνάμει ἐστίν: οὐκ ἔστι δέ, ὅτι οὐκ ἐντελεχείᾳ ἐστίν.	758. And the word actuality, which is combined with entelechy, is extended chiefly from motion to other things; for actuality seems to be identified mainly with motion. And for this reason they do not assign motion to non-existent things, but they do assign the other categories. For example, non-existent things are considered the objects of intellect and desire but not to be in motion. And the reason is that they would have to exist actually even though they did not exist actually; for some non-existent things are potential. Yet they do not exist, because they do not exist in complete actuality.
Chapter 4
εἰ δέ ἐστι τὸ εἰρημένον τὸ δυνατὸν ἢ ἀκολουθεῖ, φανερὸν ὅτι οὐκ ἐνδέχεται ἀληθὲς εἶναι τὸ εἰπεῖν ὅτι δυνατὸν μὲν [5] 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 μηδ᾽ ἔσεσθαι. ἀλλ᾽ ἐκεῖνο ἀνάγκη ἐκ [10] τῶν κειμένων, εἰ καὶ ὑποθοίμεθα εἶναι ἢ γεγονέναι ὃ οὐκ ἔστι μὲν δυνατὸν δέ, ὅτι οὐθὲν ἔσται ἀδύνατον: συμβήσεται δέ γε, τὸ γὰρ μετρεῖσθαι ἀδύνατον. οὐ γὰρ δή ἐστι ταὐτὸ τὸ ψεῦδος καὶ τὸ ἀδύνατον: τὸ γάρ σε ἑστάναι νῦν ψεῦδος μέν, οὐκ ἀδύνατον δέ.	759. Now if what has been called potential or possible is such because something follows from it, it is evident that it cannot be true to say that a thing is possible but will not be, because things which cannot possibly be would then disappear. An example would be if someone, thinking that nothing is impossible, were to affirm that it is possible for the diagonal of a square to be commensurate, even though it is not commensurate; because nothing prevents a thing that is capable of being or of coming to be from not being or not coming to be. But this conclusion necessarily follows from the things laid down above. And if we suppose that which is not but is capable I of being, to be or to have come into being, nothing would be impossible. But in this case something impossible will occur; for it is impossible that a diagonal be commensurate. For to be false and to be impossible are not the same; for while it is false that you are now standing, it is not impossible.
ἅμα δὲ δῆλον καὶ ὅτι, εἰ [15] τοῦ Α ὄντος ἀνάγκη τὸ Β εἶναι, καὶ δυνατοῦ ὄντος εἶναι τοῦ Α καὶ τὸ Β ἀνάγκη εἶναι δυνατόν: εἰ γὰρ μὴ ἀνάγκη δυνατὸν εἶναι, οὐθὲν κωλύει μὴ εἶναι δυνατὸν εἶναι. ἔστω δὴ τὸ Α δυνατόν. οὐκοῦν ὅτε τὸ Α δυνατὸν εἴη εἶναι, εἰ τεθείη τὸ Α, οὐθὲν ἀδύνατον εἶναι συνέβαινεν: τὸ δέ γε Β [20] ἀνάγκη εἶναι. ἀλλ᾽ ἦν ἀδύνατον. ἔστω δὴ ἀδύνατον. εἰ δὴ ἀδύνατον [ἀνάγκη] εἶναι τὸ Β, ἀνάγκη καὶ τὸ Α εἶναι. ἀλλ᾽ ἦν ἄρα τὸ πρῶτον ἀδύνατον: καὶ τὸ δεύτερον ἄρα. 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 [25] τῶν Α Β μὴ ᾖ δυνατὸν τὸ Β οὕτως, οὐδὲ τὰ Α Β ἕξει ὡς ἐτέθη: 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 [30] εἶναι, κἀκεῖνο τότε καὶ οὕτως εἶναι ἀναγκαῖον.	760. And at the same time it is evident that, if when A exists B must exist, then if A is possible B must be possible; for if it is not necessary that B be possible, there is nothing to prevent its not being possible. Therefore, let A be possible. And if A is possible, then when A is possible, if A is assumed to exist, nothing impossible follows, but B necessarily exists. But this was supposed to be impossible. Therefore, let B be impossible. Then if B must be impossible, A must be so. But the first was supposed to be impossible; therefore so also is the second. Hence, if A is possible, B will be possible also, i.e., if they are so related that, when A exists, B must exist. Therefore, if when A and B are so related, B is not possible, then A and B will not be related in the way supposed. On the other hand, if, when A is possible, B must be possible, then if A exists, B must exist. For to say that B must be possible if A is possible, means that, if A exists both when it exists and in the way in which it is possible for it to exist, then B must also exist and exist in that way.

ARISTOTLE’S TEXT Chapter 5: 1047b 31-1048a 24
ἁπασῶν 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 [35] καὶ τὰς ἐπὶ τοῦ πάσχειν οὐκ ἀνάγκη.	761. And since among all potencies some are innate, as the senses, and some are acquired by practice, as the power of playing the flute, and some by learning, as artistic powers, those which are acquired by practice and by the use of reason must be acquired by previous exercise. But this is not necessary in the case of those which are not such and which involve passivity.
[1048α] [1] 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 [5] εἶναι ταύτας δὲ ἐν ἀμφοῖν,	762. Now that which is capable is capable of something at some time and in some way, and has all the other qualifications which must be included in the definition; and some things can cause motion according to a rational plan and their potencies are rational, whereas other things are devoid of any rational plan and their potencies are irrational. And the former potencies must exist in living things, whereas the latter exist in both kinds of things.
τὰς μὲν τοιαύτας δυνάμεις ἀνάγκη, ὅταν ὡς δύνανται τὸ ποιητικὸν καὶ τὸ παθητικὸν πλησιάζωσι, τὸ μὲν ποιεῖν τὸ δὲ πάσχειν, ἐκείνας δ᾽ οὐκ ἀνάγκη:	763. And since this is so, then in the case of the latter potencies, when the thing that is capable of acting and the one that is capable of being acted upon come close to each other, the one must act and the other be acted upon; but in the case of the former potencies this is not necessary.
αὗται μὲν γὰρ πᾶσαι μία ἑνὸς ποιητική, ἐκεῖναι δὲ τῶν ἐναντίων, ὥστε ἅμα ποιήσει τὰ ἐναντία: τοῦτο δὲ [10] ἀδύνατον.	764. For the latter are all productive of one effect, whereas the former are productive of contrary effects. Hence they would produce contrary effects at the same time, that is, if they were to act on a proximate patient without something determining them. But this is impossible.
ἀνάγκη ἄρα ἕτερόν τι εἶναι τὸ κύριον: λέγω δὲ τοῦτο ὄρεξιν ἢ προαίρεσιν. 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, [15] τοῦτο ποιεῖν: ἔχει δὲ παρόντος τοῦ παθητικοῦ καὶ ὡδὶ ἔχοντος [ποιεῖν]: εἰ δὲ μή, ποιεῖν οὐ δυνήσεται	765. Therefore there must be some other thing which is the proper cause of this, and by this I mean appetite or choice. For whatever a thing chiefly desires this it will do, when, insofar as it is potential, it is present and comes close to the thing which is capable of being acted upon. Hence every potency endowed with reason, when it desires something of which it has the potency and insofar as it has it, must do this thing. And it has this potency when the thing capable of being acted upon is present and is disposed in a definite way; but if it is not, it will not be able to act.
(τὸ γὰρ μηθενὸς τῶν ἔξω κωλύοντος προσδιορίζεσθαι οὐθὲν ἔτι δεῖ: τὴν γὰρ δύναμιν ἔχει ὡς ἔστι δύναμις τοῦ ποιεῖν, ἔστι δ᾽ οὐ πάντως ἀλλ᾽ ἐχόντων πῶς, ἐν οἷς ἀφορισθήσεται καὶ τὰ ἔξω κωλύοντα: [20] ἀφαιρεῖται γὰρ ταῦτα τῶν ἐν τῷ διορισμῷ προσόντων ἔνια):	766. For it is unnecessary to add this qualification: when nothing external hinders it; for the agent has the potency insofar as it is a potency for acting. But this is not true of all things but only of those which are disposed in a definite way, in the case of which external obstacles will be excluded; for they remove some of the qualifications which are given in the definition of the capable or possible.
διὸ οὐδ᾽ ἐὰν ἅμα βούληται ἢ ἐπιθυμῇ ποιεῖν δύο ἢ τὰ ἐναντία, οὐ ποιήσει: οὐ γὰρ οὕτως ἔχει αὐτῶν τὴν δύναμιν οὐδ᾽ ἔστι τοῦ ἅμα ποιεῖν ἡ δύναμις, ἐπεὶ ὧν ἐστὶν οὕτως ποιήσει. [25]	767. And for this reason if such things wish or desire to do two things or contrary things at the same time, they will not do them; for they do not have the potency for doing both at the same time, nor is it possible to do them at the same time, since it is those things which they have the capacity of doing that they do.

ARISTOTLE’S TEXT Chapter 6: 1048a 25-1048b 36
ἐπεὶ δὲ περὶ τῆς κατὰ κίνησιν λεγομένης δυνάμεως εἴρηται, περὶ ἐνεργείας διορίσωμεν τί τέ ἐστιν ἡ ἐνέργεια καὶ ποῖόν τι. καὶ γὰρ τὸ δυνατὸν ἅμα δῆλον ἔσται διαιροῦσιν, ὅτι οὐ μόνον τοῦτο λέγομεν δυνατὸν ὃ πέφυκε κινεῖν ἄλλο ἢ κινεῖσθαι ὑπ᾽ ἄλλου ἢ ἁπλῶς ἢ τρόπον τινά, ἀλλὰ [30] καὶ ἑτέρως, διὸ ζητοῦντες καὶ περὶ τούτων διήλθομεν.	768. Since we have dealt with the kind of potency which is related to motion, let us now determine about actuality both what it is and what kind of thing it is. For in making our distinctions it will become evident at the same time with regard to the potential not only that we speak of the potential as that which is disposed by nature to move something else or be moved by something else, either in an unqualified sense or in some special way, but also that we use the word in a different sense as well. And for this reason we will also come upon these points in making our investigations.
ἔστι δὴ ἐνέργεια τὸ ὑπάρχειν τὸ πρᾶγμα μὴ οὕτως ὥσπερ λέγομεν δυνάμει: λέγομεν δὲ δυνάμει οἷον ἐν τῷ ξύλῳ Ἑρμῆν καὶ ἐν τῇ ὅλῃ τὴν ἡμίσειαν, ὅτι ἀφαιρεθείη ἄν, καὶ ἐπιστήμονα καὶ τὸν μὴ θεωροῦντα, ἂν δυνατὸς ᾖ θεωρῆσαι: [35] τὸ δὲ ἐνεργείᾳ.	769. Now actuality is the existence of a thing not in the sense in which we say that a thing exists potentially, as when we say that Mercury is potentially in the wood, and a half in the whole, because it can be separated from it, or as we say that one who is not theorizing is a man of science if he is able to theorize; but in the sense in which each of these exists actually.
δῆλον δ᾽ ἐπὶ τῶν καθ᾽ ἕκαστα τῇ ἐπαγωγῇ ὃ βουλόμεθα λέγειν, καὶ οὐ δεῖ παντὸς ὅρον ζητεῖν ἀλλὰ καὶ τὸ ἀνάλογον συνορᾶν, ὅτι ὡς τὸ οἰκοδομοῦν πρὸς τὸ οἰκοδομικόν, [1048β] [1] καὶ τὸ ἐγρηγορὸς πρὸς τὸ καθεῦδον, καὶ τὸ ὁρῶν πρὸς τὸ μῦον μὲν ὄψιν δὲ ἔχον, καὶ τὸ ἀποκεκριμένον ἐκ τῆς ὕλης πρὸς τὴν ὕλην, καὶ τὸ ἀπειργασμένον πρὸς τὸ ἀνέργαστον. ταύτης δὲ τῆς διαφορᾶς [5] θατέρῳ μορίῳ ἔστω ἡ ἐνέργεια ἀφωρισμένη θατέρῳ δὲ τὸ δυνατόν.	770. What we mean becomes evident in particular cases by induction, and we should not look for the boundaries of every thing, but perceive what is proportional; for it is as one who is building to one capable of building, and as one who is awake to one who is asleep, and as one who sees to one whose eyes are closed but who has the power of sight, and as that which is separated out of matter to matter, and as that which has been worked on to that which has not; and let actuality be defined by one member of this division and potency by the other.
λέγεται δὲ ἐνεργείᾳ οὐ πάντα ὁμοίως ἀλλ᾽ ἢ τῷ ἀνάλογον, ὡς τοῦτο ἐν τούτῳ ἢ πρὸς τοῦτο, τόδ᾽ ἐν τῷδε ἢ πρὸς τόδε: τὰ μὲν γὰρ ὡς κίνησις πρὸς δύναμιν τὰ δ᾽ ὡς οὐσία πρός τινα ὕλην.	771. However, things are not all said to be actual in the same way, but proportionally, as this is in that or to that; indeed, some are as motion to potency, and others as substance to some matter.
ἄλλως δὲ καὶ τὸ ἄπειρον [10] καὶ τὸ κενόν, καὶ ὅσα τοιαῦτα, λέγεται δυνάμει καὶ ἐνεργείᾳ <�ἢ> πολλοῖς τῶν ὄντων, οἷον τῷ ὁρῶντι καὶ βαδίζοντι καὶ ὁρωμένῳ. ταῦτα μὲν γὰρ ἐνδέχεται καὶ ἁπλῶς ἀληθεύεσθαί ποτε (τὸ μὲν γὰρ ὁρώμενον ὅτι ὁρᾶται, τὸ δὲ ὅτι ὁρᾶσθαι δυνατόν): τὸ δ᾽ ἄπειρον οὐχ οὕτω δυνάμει ἔστιν ὡς [15] ἐνεργείᾳ ἐσόμενον χωριστόν, ἀλλὰ γνώσει. τὸ γὰρ μὴ ὑπολείπειν τὴν διαίρεσιν ἀποδίδωσι τὸ εἶναι δυνάμει ταύτην τὴν ἐνέργειαν, τὸ δὲ χωρίζεσθαι οὔ.	772. But the infinite and the void and all other such things are said to exist potentially and actually in a different sense from that which applies to many beings, for example, from that which sees or walks or is visible. For these things can be verified, and verified without qualification; for what is visible is so designated sometimes because it is being seen and sometimes because it is capable of being seen. But the infinite does not exist potentially in the sense that it will ever have actual separate existence, but it exists potentially only in knowledge. For since the process of division never comes to an end, this shows that this actuality exists potentially, but not that it ever exists separately.’ Therefore, regarding actuality, both what it is and what kind of thing it is will be evident to us from these and similar considerations.
ἐπεὶ δὲ τῶν πράξεων ὧν ἔστι πέρας οὐδεμία τέλος ἀλλὰ τῶν περὶ τὸ τέλος, οἷον τὸ ἰσχναίνειν ἢ ἰσχνασία [20] [αὐτό], αὐτὰ δὲ ὅταν ἰσχναίνῃ οὕτως ἐστὶν ἐν κινήσει, μὴ ὑπάρχοντα ὧν ἕνεκα ἡ κίνησις, οὐκ ἔστι ταῦτα πρᾶξις ἢ οὐ τελεία γε (οὐ γὰρ τέλος): ἀλλ᾽ ἐκείνη <�ᾗ> ἐνυπάρχει τὸ τέλος καὶ [ἡ] πρᾶξις. οἷον ὁρᾷ ἅμα <�καὶ ἑώρακε,> καὶ φρονεῖ <�καὶ πεφρόνηκε,> καὶ νοεῖ καὶ νενόηκεν, ἀλλ᾽ οὐ μανθάνει καὶ μεμάθηκεν [25] οὐδ᾽ ὑγιάζεται καὶ ὑγίασται: εὖ ζῇ καὶ εὖ ἔζηκεν ἅμα, καὶ εὐδαιμονεῖ καὶ εὐδαιμόνηκεν. εἰ δὲ μή, ἔδει ἄν ποτε παύεσθαι ὥσπερ ὅταν ἰσχναίνῃ, νῦν δ᾽ οὔ, ἀλλὰ ζῇ καὶ ἔζηκεν. τούτων δὴ <�δεῖ> τὰς μὲν κινήσεις λέγειν, τὰς δ᾽ ἐνεργείας. πᾶσα γὰρ κίνησις ἀτελής, ἰσχνασία μάθησις βάδισις οἰκοδόμησις: [30] αὗται δὴ κινήσεις, καὶ ἀτελεῖς γε. οὐ γὰρ ἅμα βαδίζει καὶ βεβάδικεν, οὐδ᾽ οἰκοδομεῖ καὶ ᾠκοδόμηκεν, οὐδὲ γίγνεται καὶ γέγονεν ἢ κινεῖται καὶ κεκίνηται, ἀλλ᾽ ἕτερον, καὶ κινεῖ καὶ κεκίνηκεν: ἑώρακε δὲ καὶ ὁρᾷ ἅμα τὸ αὐτό, καὶ νοεῖ καὶ νενόηκεν. τὴν μὲν οὖν τοιαύτην ἐνέργειαν [35] λέγω, ἐκείνην δὲ κίνησιν.

ARISTOTLE’S TEXT Chapter 7: 1048b 37-1049b 3
τὸ μὲν οὖν ἐνεργείᾳ τί τέ ἐστι καὶ ποῖον, ἐκ τούτων καὶ τῶν τοιούτων δῆλον ἡμῖν ἔστω. πότε δὲ δυνάμει ἔστιν ἕκαστον καὶ πότε οὔ, διοριστέον: οὐ γὰρ ὁποτεοῦν. [1049α] [1] οἷον ἡ γῆ ἆρ᾽ ἐστὶ δυνάμει ἄνθρωπος; ἢ οὔ, ἀλλὰ μᾶλλον ὅταν ἤδη γένηται σπέρμα, καὶ οὐδὲ τότε ἴσως;	773. However, we must determine when each thing is in a state of potency and when it is not; for a thing is not potential at just any time at all; for example, in the process of generation is earth. potentially a man? Or is it not, but rather when it has become seed? But perhaps even this is not true in an unqualified sense.
ὥσπερ οὖν οὐδ᾽ ὑπὸ ἰατρικῆς ἅπαν ἂν ὑγιασθείη οὐδ᾽ ἀπὸ τύχης, ἀλλ᾽ ἔστι τι ὃ δυνατόν ἐστι, καὶ τοῦτ᾽ ἔστιν [5] ὑγιαῖνον δυνάμει. ὅρος δὲ τοῦ μὲν ἀπὸ διανοίας ἐντελεχείᾳ γιγνομένου ἐκ τοῦ δυνάμει ὄντος, ὅταν βουληθέντος γίγνηται μηθενὸς κωλύοντος τῶν ἐκτός, ἐκεῖ δ᾽ ἐν τῷ ὑγιαζομένῳ, ὅταν μηθὲν κωλύῃ τῶν ἐν αὐτῷ: ὁμοίως δὲ δυνάμει καὶ οἰκία: εἰ μηθὲν κωλύει τῶν ἐν τούτῳ καὶ τῇ [10] ὕλῃ τοῦ γίγνεσθαι οἰκίαν, οὐδ᾽ ἔστιν ὃ δεῖ προσγενέσθαι ἢ ἀπογενέσθαι ἢ μεταβαλεῖν, τοῦτο δυνάμει οἰκία: καὶ ἐπὶ τῶν ἄλλων ὡσαύτως ὅσων ἔξωθεν ἡ ἀρχὴ τῆς γενέσεως. καὶ ὅσων δὴ ἐν αὐτῷ τῷ ἔχοντι, ὅσα μηθενὸς τῶν ἔξωθεν ἐμποδίζοντος ἔσται δι᾽ αὐτοῦ: οἷον τὸ σπέρμα οὔπω (δεῖ γὰρ [15] ἐν ἄλλῳ <�πεσεῖν> καὶ μεταβάλλειν), ὅταν δ᾽ ἤδη διὰ τῆς αὑτοῦ ἀρχῆς ᾖ τοιοῦτον, ἤδη τοῦτο δυνάμει: ἐκεῖνο δὲ ἑτέρας ἀρχῆς δεῖται, ὥσπερ ἡ γῆ οὔπω ἀνδριὰς δυνάμει (μεταβαλοῦσα γὰρ ἔσται χαλκός).	774. Therefore, in like manner, it is not everything which will be healed by the art of medicine or by chance, but there is something which is capable of being healed, and this is what is potentially healthy. And the intelligible expression of what comes to exist actually after existing potentially as a result of intellect is that it is something which when willed comes to be if no external impediment hinders it. And in the other case, namely, in that of the thing which gets well by itself, health exists potentially when nothing within the thing hinders it. The same is true of those things which are potentially a house; for if there is nothing in these things, i.e., in the matter, which prevents them from becoming a house, and if there is nothing which must be added or taken away or changed, this is potentially a house. The same is true of all other things which have an external principle of generation. And in the case of those things which have their principle of change within themselves, a thing will also be potentially any of those things which it will be of itself if nothing external hinders this. For example, seed is not yet such, because it must be present in some other thing and be changed. But when it is already such as a result of its own principle, it is now this thing potentially; but in the other state it needs another principle; for example, earth is not yet a statue potentially, but when changed it becomes bronze.
ἔοικε δὲ ὃ λέγομεν εἶναι οὐ τόδε ἀλλ᾽ ἐκείνινον—οἷον τὸ κιβώτιον οὐ ξύλον ἀλλὰ ξύλινον, [20] οὐδὲ τὸ ξύλον γῆ ἀλλὰ γήϊνον, πάλιν ἡ γῆ εἰ οὕτως μὴ ἄλλο ἀλλὰ ἐκείνινον—ἀεὶ ἐκεῖνο δυνάμει ἁπλῶς τὸ ὕστερόν ἐστιν. οἷον τὸ κιβώτιον οὐ γήϊνον οὐδὲ γῆ ἀλλὰ ξύλινον: τοῦτο γὰρ δυνάμει κιβώτιον καὶ ὕλη κιβωτίου αὕτη, ἁπλῶς μὲν τοῦ ἁπλῶς τουδὶ δὲ τοδὶ τὸ ξύλον. εἰ δέ τί ἐστι πρῶτον [25] ὃ μηκέτι κατ᾽ ἄλλο λέγεται ἐκείνινον, τοῦτο πρώτη ὕλη: οἷον εἰ ἡ γῆ ἀερίνη, ὁ δ᾽ ἀὴρ μὴ πῦρ ἀλλὰ πύρινος, τὸ πῦρ ὕλη πρώτη οὐ τόδε τι οὖσα. τούτῳ γὰρ διαφέρει τὸ καθ᾽ οὗ καὶ τὸ ὑποκείμενον, τῷ εἶναι τόδε τι ἢ μὴ εἶναι:	775. Now it seems that the thing of which we are speaking is not a that but a “thaten”; for example, a chest is not wood but wooden; and wood is not earth but earthen. And the same thing would be true if earth were not something else but a “thaten.” And that other thing is always potentially (in an unqualified sense) the thing which follows it, as a chest is not earth or earthen but wooden; for this is potentially a chest and the matter of a chest; and wood in an unqualified sense is the matter of a chest in an unqualified sense; but this wood is the matter of this chest. And if there is some first thing which is not said to be “thaten” as regards something else, this is prime matter; for example, if earth is of air, and air is not fire but of fire, then fire is prime matter, and is a particular thing. For a universal and a subject differ in this respect that a subject is a particular thing.
οἷον τοῖς πάθεσι τὸ ὑποκείμενον ἄνθρωπος καὶ [30] σῶμα καὶ ψυχή, πάθος δὲ τὸ μουσικὸν καὶ λευκόν (λέγεται δὲ τῆς μουσικῆς ἐγγενομένης ἐκεῖνο οὐ μουσικὴ ἀλλὰ μουσικόν, καὶ οὐ λευκότης ὁ ἄνθρωπος ἀλλὰ λευκόν, οὐδὲ βάδισις ἢ κίνησις ἀλλὰ βαδίζον ἢ κινούμενον, ὡς τὸ ἐκείνινον):	776. For example, the subject of modifications is man, body and animal, whereas the modification is musical or white. And when music comes to a subject, the subject is not called music but musical; and a man is not called whiteness but white; and he is not called walking or motion but what walks or is moved, like a “thaten.”
ὅσα μὲν οὖν οὕτω, τὸ ἔσχατον οὐσία: ὅσα δὲ μὴ [35] οὕτως ἀλλ᾽ εἶδός τι καὶ τόδε τι τὸ κατηγορούμενον, τὸ ἔσχατον ὕλη καὶ οὐσία ὑλική. καὶ ὀρθῶς δὴ συμβαίνει τὸ ἐκείνινον λέγεσθαι κατὰ τὴν ὕλην καὶ τὰ πάθη: [1049β] [1] ἄμφω γὰρ ἀόριστα. πότε μὲν οὖν λεκτέον δυνάμει καὶ πότε οὔ, εἴρηται.	777. Therefore all those modifying attributes which are predicated in this way have substance as their ultimate subject; whereas those which are not predicated in this way, but the predicate is a form or a particular thing, have matter and material substance as their ultimate subject. Therefore it is only fitting that the term “thaten” happens to be predicated of matter and the modifying attributes; for both are indeterminate. It has been stated, then, when a thing is said to exist potentially, and when it is not.

ARISTOTLE’S TEXT Chapter 8: 1049b 4-1050a 3
ἐπεὶ δὲ τὸ πρότερον διώρισται ποσαχῶς λέγεται, [5] φανερὸν ὅτι πρότερον ἐνέργεια δυνάμεώς ἐστιν. λέγω δὲ δυνάμεως οὐ μόνον τῆς ὡρισμένης ἣ λέγεται ἀρχὴ μεταβλητικὴ ἐν ἄλλῳ ἢ ᾗ ἄλλο, ἀλλ᾽ ὅλως πάσης ἀρχῆς κινητικῆς ἢ στατικῆς. καὶ γὰρ ἡ φύσις ἐν ταὐτῷ [γίγνεται: ἐν ταὐτῷ γὰρ] γένει τῇ δυνάμει: ἀρχὴ γὰρ κινητική, ἀλλ᾽ [10] οὐκ ἐν ἄλλῳ ἀλλ᾽ ἐν αὐτῷ ᾗ αὐτό. πάσης δὴ τῆς τοιαύτης προτέρα ἐστὶν ἡ ἐνέργεια καὶ λόγῳ καὶ τῇ οὐσίᾳ: χρόνῳ δ᾽ ἔστι μὲν ὥς, ἔστι δὲ ὡς οὔ.	778. Since we have established the different senses in which the term prior is employed (457), it is evident that actuality is prior to potency. And by potency I mean not only that definite kind which is said to be a principle of change in another thing inasmuch as it is other, but in general every principle of motion or rest. For nature also belongs to the same thing, since it is in the same genus as potency; for it is a principle of motion, although not in another thing but in something inasmuch as it is the same. Therefore actuality is prior to all such potency both in intelligibility and in substance; and in time it is prior in one sense, and in another it is not.
τῷ λόγῳ μὲν οὖν ὅτι προτέρα, δῆλον (τῷ γὰρ ἐνδέχεσθαι ἐνεργῆσαι δυνατόν ἐστι τὸ πρώτως δυνατόν, οἷον λέγω οἰκοδομικὸν τὸ δυνάμενον οἰκοδομεῖν, [15] καὶ ὁρατικὸν τὸ ὁρᾶν, καὶ ὁρατὸν τὸ δυνατὸν ὁρᾶσθαι: ὁ δ᾽ αὐτὸς λόγος καὶ ἐπὶ τῶν ἄλλων, ὥστ᾽ ἀνάγκη τὸν λόγον προϋπάρχειν καὶ τὴν γνῶσιν τῆς γνώσεως):	779. It is evident, then, that actuality is prior to potency in intelligibility; for what is potential in a primary sense is potential because it is possible for it to become actual. I mean, for example, that it is what is capable of building that can build, and what is capable of theorizing that can theorize, and what is capable of being seen that can be seen. And the same reasoning also applies in the case of other things; and therefore it is necessary that the conception or knowledge of the one should precede that of the other.
δὲ χρόνῳ πρότερον ὧδε: τὸ τῷ εἴδει τὸ αὐτὸ ἐνεργοῦν πρότερον, ἀριθμῷ δ᾽ οὔ. λέγω δὲ τοῦτο ὅτι τοῦδε μὲν τοῦ ἀνθρώπου τοῦ [20] ἤδη ὄντος κατ᾽ ἐνέργειαν καὶ τοῦ σίτου καὶ τοῦ ὁρῶντος πρότερον τῷ χρόνῳ ἡ ὕλη καὶ τὸ σπέρμα καὶ τὸ ὁρατικόν, ἃ δυνάμει μέν ἐστιν ἄνθρωπος καὶ σῖτος καὶ ὁρῶν, ἐνεργείᾳ δ᾽ οὔπω: ἀλλὰ τούτων πρότερα τῷ χρόνῳ ἕτερα ὄντα ἐνεργείᾳ ἐξ ὧν ταῦτα ἐγένετο: ἀεὶ γὰρ ἐκ τοῦ δυνάμει ὄντος [25] γίγνεται τὸ ἐνεργείᾳ ὂν ὑπὸ ἐνεργείᾳ ὄντος, οἷον ἄνθρωπος ἐξ ἀνθρώπου, μουσικὸς ὑπὸ μουσικοῦ, ἀεὶ κινοῦντός τινος πρώτου: τὸ δὲ κινοῦν ἐνεργείᾳ ἤδη ἔστιν. εἴρηται δὲ ἐν τοῖς περὶ τῆς οὐσίας λόγοις ὅτι πᾶν τὸ γιγνόμενον γίγνεται ἔκ τινος τι καὶ ὑπό τινος, καὶ τοῦτο τῷ εἴδει τὸ αὐτό.	780. And actuality is prior to potency in time in the sense that an actuality which is specifically but not numerically the same as a potency is prior to it. I mean that the matter and & seed and the thing capable of seeing, which are a man and grain and seeing potentially but not yet actually, are prior in time to this man and to grain and to the act of seeing which exist actually. But prior to these are other actually existing things from which these have been produced; for what is actual is always produced from something potential by means of something which is actual. Thus man comes from man and musician from musician; for there is always some primary mover, and a mover is already something actual. And in our previous discussions (598; 611) concerning substance it was stated that everything which comes to be is produced from something, and this is specifically the same as itself.
διὸ καὶ δοκεῖ [30] ἀδύνατον εἶναι οἰκοδόμον εἶναι μὴ οἰκοδομήσαντα μηθὲν ἢ κιθαριστὴν μηθὲν κιθαρίσαντα: ὁ γὰρ μανθάνων κιθαρίζειν κιθαρίζων μανθάνει κιθαρίζειν, ὁμοίως δὲ καὶ οἱ ἄλλοι.	781. And for this reason it seems to be impossible that anyone should be a builder who has not built something, or that anyone should be a harpist who has not played the harp. And the same holds true of all others who are learning; for one who is learning to play the harp learns to play it by playing it. And the same holds true in other cases.
ὅθεν ὁ σοφιστικὸς ἔλεγχος ἐγίγνετο ὅτι οὐκ ἔχων τις τὴν ἐπιστήμην ποιήσει οὗ ἡ ἐπιστήμη: ὁ γὰρ μανθάνων οὐκ ἔχει.	782. From this arose the sophistical argument that one who does not have a science will be doing the thing which is the object of this science; for one who is learning a science does not have it.
[35] ἀλλὰ διὰ τὸ τοῦ γιγνομένου γεγενῆσθαί τι καὶ τοῦ ὅλως κινουμένου κεκινῆσθαί τι (δῆλον δ᾽ ἐν τοῖς περὶ κινήσεως τοῦτο) [1050α] [1] καὶ τὸν μανθάνοντα ἀνάγκη ἔχειν τι τῆς ἐπιστήμης ἴσως. ἀλλ᾽ οὖν καὶ ταύτῃ γε δῆλον ὅτι ἡ ἐνέργεια καὶ οὕτω προτέρα τῆς δυνάμεως κατὰ γένεσιν καὶ χρόνον.	783. But since some part of what is coming to be has come to be, and in general some part of what is being moved has been moved (as became evident in our discussions on motion), perhaps one who is learning a science must have some part of that science. Hence it is also clear from this that actuality is prior to potency both in the process of generation and in time.

ARISTOTLE’S TEXT Chapter 8: 1050a 4-1050b 6
ἀλλὰ μὴν καὶ οὐσίᾳ γε, πρῶτον μὲν ὅτι τὰ τῇ γενέσει [5] ὕστερα τῷ εἴδει καὶ τῇ οὐσίᾳ πρότερα (οἷον ἀνὴρ παιδὸς καὶ ἄνθρωπος σπέρματος: τὸ μὲν γὰρ ἤδη ἔχει τὸ εἶδος τὸ δ᾽ οὔ),	784. But actuality is also prior in substance; (1) because those things which are subsequent in generation are prior in form and substance; for example, man is prior to boy, and human being to seed; for the one already has its form, but the other has not.
καὶ ὅτι ἅπαν ἐπ᾽ ἀρχὴν βαδίζει τὸ γιγνόμενον καὶ τέλος (ἀρχὴ γὰρ τὸ οὗ ἕνεκα, τοῦ τέλους δὲ ἕνεκα ἡ γένεσις), τέλος δ᾽ ἡ ἐνέργεια, καὶ τούτου χάριν ἡ δύναμις [10] λαμβάνεται. οὐ γὰρ ἵνα ὄψιν ἔχωσιν ὁρῶσι τὰ ζῷα ἀλλ᾽ ὅπως ὁρῶσιν ὄψιν ἔχουσιν, ὁμοίως δὲ καὶ οἰκοδομικὴν ἵνα [12] οἰκοδομῶσι καὶ τὴν θεωρητικὴν ἵνα θεωρῶσιν: ἀλλ᾽ οὐ θεωροῦσιν ἵνα θεωρητικὴν ἔχωσιν, εἰ μὴ οἱ μελετῶντες: οὗτοι δὲ οὐχὶ θεωροῦσιν ἀλλ᾽ ἢ ὡδί, ἢ ὅτι οὐδὲν δέονται θεωρεῖν.	785. And (2) because everything which comes to be moves toward a principle, namely, its goal [or end]. For that for the sake of which a thing comes to be is a principle; and generation is for the sake of the goal. And actuality is the goal, and it is for the sake of this that potency is acquired.
καὶ ὅτι ἅπαν ἐπ᾽ ἀρχὴν βαδίζει τὸ γιγνόμενον καὶ τέλος (ἀρχὴ γὰρ τὸ οὗ ἕνεκα,	786. For animals do not see in order that they may have the power of sight, but they have the power of sight in order that they may see.
τοῦ τέλους δὲ ἕνεκα ἡ γένεσις), τέλος δ᾽ ἡ ἐνέργεια, καὶ τούτου χάριν ἡ δύναμις [10] λαμβάνεται. οὐ γὰρ ἵνα ὄψιν ἔχωσιν ὁρῶσι τὰ ζῷα ἀλλ᾽ ὅπως ὁρῶσιν ὄψιν ἔχουσιν, ὁμοίως δὲ καὶ οἰκοδομικὴν ἵνα [12] οἰκοδομῶσι καὶ τὴν θεωρητικὴν ἵνα θεωρῶσιν: ἀλλ᾽ οὐ θεωροῦσιν ἵνα θεωρητικὴν ἔχωσιν, εἰ μὴ οἱ μελετῶντες: οὗτοι δὲ οὐχὶ θεωροῦσιν ἀλλ᾽ ἢ ὡδί, ἢ ὅτι οὐδὲν δέονται θεωρεῖν.	787. And similarly men have the science of building in order that they may build, and they have theoretical knowledge in order that they may speculate; but they do not speculate in order that they may have theoretical knowledge, unless they are learning by practice. And these latter do not speculate [in a perfect way], but either to some degree or because they do not need to speculate.
[15] ἔτι ἡ ὕλη ἔστι δυνάμει ὅτι ἔλθοι ἂν εἰς τὸ εἶδος: ὅταν δέ γε ἐνεργείᾳ ᾖ, τότε ἐν τῷ εἴδει ἐστίν. ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων, καὶ ὧν κίνησις τὸ τέλος, διὸ ὥσπερ οἱ διδάσκοντες ἐνεργοῦντα ἐπιδείξαντες οἴονται τὸ τέλος ἀποδεδωκέναι, καὶ ἡ φύσις ὁμοίως.	788. Further, matter is in potency up to the time at which it attains its form; but when it exists actually, it then possesses its form. And the same holds true in the case of other things, even of those whose goal is motion. And for this reason, just as those who are teaching think that they have reached their goal when they exhibit their student performing, so it is with nature.
εἰ γὰρ μὴ οὕτω γίγνεται, ὁ [20] Παύσωνος ἔσται Ἑρμῆς: ἄδηλος γὰρ καὶ ἡ ἐπιστήμη εἰ ἔσω ἢ ἔξω, ὥσπερ κἀκεῖνος. τὸ γὰρ ἔργον τέλος, ἡ δὲ ἐνέργεια τὸ ἔργον, διὸ καὶ τοὔνομα ἐνέργεια λέγεται κατὰ τὸ ἔργον καὶ συντείνει πρὸς τὴν ἐντελέχειαν.	789. For if this were not so, Pauson’s Mercury would exist again, because it would not be more evident whether scientific knowledge is internal or external, as is the case with the figure of Mercury. For the activity is the goal, and the actuality is the activity. And for this reason the term actuality is used in reference to activity and is extended to completeness.
ἐπεὶ δ᾽ ἐστὶ τῶν μὲν ἔσχατον ἡ χρῆσις (οἷον ὄψεως ἡ ὅρασις, καὶ οὐθὲν [25] γίγνεται παρὰ ταύτην ἕτερον ἀπὸ τῆς ὄψεως), ἀπ᾽ ἐνίων δὲ γίγνεταί τι (οἷον ἀπὸ τῆς οἰκοδομικῆς οἰκία παρὰ τὴν οἰκοδόμησιν), ὅμως οὐθὲν ἧττον ἔνθα μὲν τέλος, ἔνθα δὲ μᾶλλον τέλος τῆς δυνάμεώς ἐστιν: ἡ γὰρ οἰκοδόμησις ἐν τῷ οἰκοδομουμένῳ, καὶ ἅμα γίγνεται καὶ ἔστι τῇ οἰκίᾳ. [30] ὅσων μὲν οὖν ἕτερόν τί ἐστι παρὰ τὴν χρῆσιν τὸ γιγνόμενον, τούτων μὲν ἡ ἐνέργεια ἐν τῷ ποιουμένῳ ἐστίν (οἷον ἥ τε οἰκοδόμησις ἐν τῷ οἰκοδομουμένῳ καὶ ἡ ὕφανσις ἐν τῷ ὑφαινομένῳ, ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων, καὶ ὅλως ἡ κίνησις ἐν τῷ κινουμένῳ): ὅσων δὲ μὴ ἔστιν ἄλλο τι ἔργον [35] παρὰ τὴν ἐνέργειαν, ἐν αὐτοῖς ὑπάρχει ἡ ἐνέργεια (οἷον ἡ ὅρασις ἐν τῷ ὁρῶντι καὶ ἡ θεωρία ἐν τῷ θεωροῦντι καὶ ἡ ζωὴ ἐν τῇ ψυχῇ, διὸ καὶ ἡ εὐδαιμονία: [1050β] [1] ζωὴ γὰρ ποιά τίς ἐστιν).	790. But while in the case of some things the ultimate effect is the use (as, for example, in the case of sight the ultimate effect is the act of seeing, and no other work besides this results from the power of sight), still from some potencies something else is produced; for example, the art of building produces a house in addition to the act of building. Yet in neither case is the act any less or any more the end of the potency; for the act of building is in the thing being built, and it comes into being and exists simultaneously with the house. Therefore in those cases in which the result is something other than the use, the actuality is in the thing being produced; for example, the act of building is in the thing being built, and the act of weaving in the thing being woven. The same holds true in all other cases. And in general, motion is in the thing being moved. But in the case of those things in which nothing else is produced besides the activity, the activity is present in these, as the act of seeing is in the one seeing, and the act of speculating in the one speculating, and life in the soul. Accordingly, happiness is in the soul, for it is a kind of life.
ὥστε φανερὸν ὅτι ἡ οὐσία καὶ τὸ εἶδος ἐνέργειά ἐστιν. κατά τε δὴ τοῦτον τὸν λόγον φανερὸν ὅτι πρότερον τῇ οὐσίᾳ ἐνέργεια δυνάμεως, καὶ ὥσπερ εἴπομεν, τοῦ χρόνου [5] ἀεὶ προλαμβάνει ἐνέργεια ἑτέρα πρὸ ἑτέρας ἕως τῆς τοῦ ἀεὶ κινοῦντος πρώτως.	791. It is evident, then, that substance or form is actuality. Hence it is clear according to this argument that actuality is prior to potency in substance. And, as we have said (780), one actuality is always prior to another in time right back to that actuality which is always the first principle of motion.

ARISTOTLE’S TEXT Chapter 8: 1050b 6-1051a 3
ἀλλὰ μὴν καὶ κυριωτέρως: τὰ μὲν γὰρ ἀΐδια πρότερα τῇ οὐσίᾳ τῶν φθαρτῶν, ἔστι δ᾽ οὐθὲν δυνάμει ἀΐδιον.	792. But actuality is prior to potency in a more fundamental sense; for eternal things are prior in substance to corruptible ones, and nothing eternal is potential.
λόγος δὲ ὅδε: πᾶσα δύναμις ἅμα τῆς ἀντιφάσεώς ἐστιν: τὸ μὲν γὰρ μὴ δυνατὸν ὑπάρχειν οὐκ [10] ἂν ὑπάρξειεν οὐθενί, τὸ δυνατὸν δὲ πᾶν ἐνδέχεται μὴ ἐνεργεῖν. τὸ ἄρα δυνατὸν εἶναι ἐνδέχεται καὶ εἶναι καὶ μὴ εἶναι: τὸ αὐτὸ ἄρα δυνατὸν καὶ εἶναι καὶ μὴ εἶναι. τὸ δὲ δυνατὸν μὴ εἶναι ἐνδέχεται μὴ εἶναι: τὸ δὲ ἐνδεχόμενον μὴ εἶναι φθαρτόν, ἢ ἁπλῶς ἢ τοῦτο αὐτὸ ὃ λέγεται [15] ἐνδέχεσθαι μὴ εἶναι, ἢ κατὰ τόπον ἢ κατὰ τὸ ποσὸν ἢ ποιόν: ἁπλῶς δὲ τὸ κατ᾽ οὐσίαν.	793. The reason of this is that every potency is at the same time a potency for opposite determinations. For what is incapable of existing does not exist in any way; and it is possible for everything that is capable of existing not to exist actually. Therefore whatever is capable of existing may either be or not be, and thus the same thing is capable both of being and of not being. But what is capable of not being may possibly not be; and what may possibly not be is corruptible: either absolutely, or in the sense in which it is said to be possible for it not to be, either according to place or to quantity or to quality. And the term absolutely means in reference to substance.
οὐθὲν ἄρα τῶν ἀφθάρτων ἁπλῶς δυνάμει ἔστιν ἁπλῶς (κατά τι δὲ οὐδὲν κωλύει, οἷον ποιὸν ἢ πού): ἐνεργείᾳ ἄρα πάντα:	794. Therefore nothing that is incorruptible in an absolute sense is potential in an absolute sense. But there is nothing that hinders it from being so in other respects, for example, in reference to quality or to place. Therefore all incorruptible things are actual.
οὐδὲ τῶν ἐξ ἀνάγκης ὄντων (καίτοι ταῦτα πρῶτα: εἰ γὰρ ταῦτα μὴ ἦν, οὐθὲν ἂν ἦν):	795. And none of those things which exist necessarily are potential. In fact such things are the first; for if they did not exist, nothing would exist.
[20] οὐδὲ δὴ κίνησις, εἴ τίς ἐστιν ἀΐδιος: οὐδ᾽ εἴ τι κινούμενον ἀΐδιον, οὐκ ἔστι κατὰ δύναμιν κινούμενον ἀλλ᾽ ἢ ποθὲν ποί (τούτου δ᾽ ὕλην οὐδὲν κωλύει ὑπάρχειν),	796. Nor is eternal motion potential, if there be such a thing; and if anything is moved eternally, it is not moved potentially except in reference to whence and whither. And nothing prevents the matter of this sort of thing from existing.
διὸ ἀεὶ ἐνεργεῖ ἥλιος καὶ ἄστρα καὶ ὅλος ὁ οὐρανός, καὶ οὐ φοβερὸν μή ποτε στῇ, ὃ φοβοῦνται οἱ περὶ φύσεως. οὐδὲ κάμνει τοῦτο δρῶντα: οὐ [25] γὰρ περὶ τὴν δύναμιν τῆς ἀντιφάσεως αὐτοῖς, οἷον τοῖς φθαρτοῖς, ἡ κίνησις, ὥστε ἐπίπονον εἶναι τὴν συνέχειαν τῆς κινήσεως: ἡ γὰρ οὐσία ὕλη καὶ δύναμις οὖσα, οὐκ ἐνέργεια, αἰτία τούτου.	797. And for this reason the sun and the stars and the entire heaven are always active, and there is no need to fear, as the natural philosophers do, that they may at some time stand still. Nor do they tire in their activity; for in them there is no potency for opposite determinations, as there is in corruptible things, so that the continuity of their motion should be tiresome. For the cause of this is that their substance is matter and potency and not actuality.
μιμεῖται δὲ τὰ ἄφθαρτα καὶ τὰ ἐν μεταβολῇ ὄντα, οἷον γῆ καὶ πῦρ. καὶ γὰρ ταῦτα ἀεὶ ἐνεργεῖ: [30] καθ᾽ αὑτὰ γὰρ καὶ ἐν αὑτοῖς ἔχει τὴν κίνησιν.	798. Moreover, incorruptible things are imitated by those which are in a state of change, such as fire and earth; for these latter things are always active, since they have motion in themselves and of themselves.
αἱ δὲ ἄλλαι δυνάμεις, ἐξ ὧν διώρισται, πᾶσαι τῆς ἀντιφάσεώς εἰσιν: τὸ γὰρ δυνάμενον ὡδὶ κινεῖν δύναται καὶ μὴ ὡδί, ὅσα γε κατὰ λόγον: αἱ δ᾽ ἄλογοι τῷ παρεῖναι καὶ μὴ τῆς ἀντιφάσεως ἔσονται αἱ αὐταί.	799. But all other potencies which have been defined are potencies for opposite determinations; for what is capable of moving something else in this way is also capable of not moving it in this way, i.e., all those things which act by reason. And irrational potencies will also be potencies for opposite determinations by being absent or not.
εἰ ἄρα τινὲς εἰσὶ φύσεις [35] τοιαῦται ἢ οὐσίαι οἵας λέγουσιν οἱ ἐν τοῖς λόγοις τὰς ἰδέας, πολὺ μᾶλλον ἐπιστῆμον ἄν τι εἴη ἢ αὐτὸ ἐπιστήμη καὶ κινούμενον ἢ κίνησις: [1051α] [1] ταῦτα γὰρ ἐνέργειαι μᾶλλον, ἐκεῖναι δὲ δυνάμεις τούτων. ὅτι μὲν οὖν πρότερον ἡ ἐνέργεια καὶ δυνάμεως καὶ πάσης ἀρχῆς μεταβλητικῆς, φανερόν.	800. If, then, there are any natures or substances such as those thinkers who in their theories proclaim the Ideas to be, there will be something much more scientific than science itself, and something much more mobile than motion itself; for the former will rather be the actualities and the latter the potencies of these. Hence it is evident that actuality is prior to potency and to every principle of change.

ARISTOTLE’S TEXT Chapter 9: 1051a 4-1051a 33
ὅτι δὲ καὶ βελτίων καὶ τιμιωτέρα τῆς σπουδαίας [5] δυνάμεως ἡ ἐνέργεια, ἐκ τῶνδε δῆλον. ὅσα γὰρ κατὰ τὸ δύνασθαι λέγεται, ταὐτόν ἐστι δυνατὸν τἀναντία, οἷον τὸ δύνασθαι λεγόμενον ὑγιαίνειν ταὐτόν ἐστι καὶ τὸ νοσεῖν, καὶ ἅμα: ἡ αὐτὴ γὰρ δύναμις τοῦ ὑγιαίνειν καὶ κάμνειν, καὶ ἠρεμεῖν καὶ κινεῖσθαι, καὶ οἰκοδομεῖν καὶ καταβάλλειν, [10] καὶ οἰκοδομεῖσθαι καὶ καταπίπτειν. τὸ μὲν οὖν δύνασθαι τἀναντία ἅμα ὑπάρχει: τὰ δ᾽ ἐναντία ἅμα ἀδύνατον, καὶ τὰς ἐνεργείας δὲ ἅμα ἀδύνατον ὑπάρχειν (οἷον ὑγιαίνειν καὶ κάμνειν), ὥστ᾽ ἀνάγκη τούτων θάτερον εἶναι τἀγαθόν, τὸ δὲ δύνασθαι ὁμοίως ἀμφότερον ἢ οὐδέτερον: [15] ἡ ἄρα ἐνέργεια βελτίων.	801. Furthermore, that actuality is also better and more excellent and more honorable than good potency is evident from the following: all things which are spoken of as potential are alike capable of contrary determinations; for example, what is said to be capable of being well is the same as what is capable of being ill, and simultaneously has both capabilities; for it is the same potency that is capable of being well and being ill, and of being at rest and in motion, and of building and demolishing, and of being built and being demolished. Therefore the capacity for contrary determinations belongs to the same thing at the same time; but it is impossible for contrary determinations to belong to the same thing at the same time, for example, being well and ailing. Hence one of these must be good; but the potency may be both alike or neither; and therefore the actuality is better.
ἀνάγκη δὲ καὶ ἐπὶ τῶν κακῶν τὸ τέλος καὶ τὴν ἐνέργειαν εἶναι χεῖρον τῆς δυνάμεως: τὸ γὰρ δυνάμενον ταὐτὸ ἄμφω τἀναντία.	802. And also in the case of evil things the goal or actuality must be worse than the potency; for it is the same potency that is capable of both contraries.
δῆλον ἄρα ὅτι οὐκ ἔστι τὸ κακὸν παρὰ τὰ πράγματα: ὕστερον γὰρ τῇ φύσει τὸ κακὸν τῆς δυνάμεως.	803. It is clear, then, that evil does not exist apart from things; for evil is by its very nature subsequent to potency.
οὐκ ἄρα οὐδ᾽ ἐν τοῖς ἐξ ἀρχῆς [20] καὶ τοῖς ἀϊδίοις οὐθὲν ἔστιν οὔτε κακὸν οὔτε ἁμάρτημα οὔτε διεφθαρμένον (καὶ γὰρ ἡ διαφθορὰ τῶν κακῶν ἐστίν).	804. Hence in those things which exist from the very beginning and are eternal, there is neither evil nor wrong nor corruption; for corruption belongs to evil things.
εὑρίσκεται δὲ καὶ τὰ διαγράμματα ἐνεργείᾳ: διαιροῦντες γὰρ εὑρίσκουσιν. εἰ δ᾽ ἦν διῃρημένα, φανερὰ ἂν ἦν: νῦν δ᾽ ἐνυπάρχει δυνάμει. διὰ τί δύο ὀρθαὶ τὸ τρίγωνον; ὅτι αἱ [25] περὶ μίαν στιγμὴν γωνίαι ἴσαι δύο ὀρθαῖς. εἰ οὖν ἀνῆκτο ἡ παρὰ τὴν πλευράν, ἰδόντι ἂν ἦν εὐθὺς δῆλον διὰ τί. ἐν ἡμικυκλίῳ ὀρθὴ καθόλου διὰ τί; ἐὰν ἴσαι τρεῖς, ἥ τε βάσις δύο καὶ ἡ ἐκ μέσου ἐπισταθεῖσα ὀρθή, ἰδόντι δῆλον τῷ ἐκεῖνο εἰδότι. ὥστε φανερὸν ὅτι τὰ δυνάμει ὄντα εἰς [30] ἐνέργειαν ἀγόμενα εὑρίσκεται: αἴτιον δὲ ὅτι ἡ νόησις ἐνέργεια: ὥστ᾽ ἐξ ἐνεργείας ἡ δύναμις, καὶ διὰ τοῦτο ποιοῦντες γιγνώσκουσιν (ὕστερον γὰρ γενέσει ἡ ἐνέργεια ἡ κατ᾽ ἀριθμόν).	805. And it is also by activity that geometrical constructions are discovered, because they are discovered by dividing. For if they had already been divided, they would be evident; but they are now present potentially. Why, for example, are the angles of a triangle equal to two right angles? Because the angles grouped around one point are equal to two right angles. Hence, if the line next to the one side were extended, the answer would be clear to anyone seeing the construction. Again, why is an angle in a semicircle always a right angle? Because, if its three lines are equal, two of which form the base and the other rests upon the middle point of the base, the answer will be evident to anyone who sees the construction and knows the former proposition. Hence, it is evident that constructions which exist potentially are discovered when they are brought to actuality; and the reason is that the intellectual comprehension of a thing is an actuality. Hence the potency proceeds from an actuality, and it is because people make these constructions that they attain knowledge of them. For in a thing numerically one and the same, actuality is subsequent in the order of generation.

ARISTOTLE’S TEXT Chapter 10: 1051a 34-1052a 11
ἐπεὶ δὲ τὸ ὂν λέγεται καὶ τὸ μὴ ὂν τὸ μὲν κατὰ [35] τὰ σχήματα τῶν κατηγοριῶν, τὸ δὲ κατὰ δύναμιν ἢ ἐνέργειαν τούτων ἢ τἀναντία, [1051β] [1] τὸ δὲ [κυριώτατα ὂν] ἀληθὲς ἢ ψεῦδος,	806. Now the terms being and non-being are used in one sense with reference to the categorical figures; and in another with reference to the potentiality or actuality of these or their contraries; and in still another sense they are referred most properly to truth and falsity.
τοῦτο δ᾽ ἐπὶ τῶν πραγμάτων ἐστὶ τῷ συγκεῖσθαι ἢ διῃρῆσθαι, ὥστε ἀληθεύει μὲν ὁ τὸ διῃρημένον οἰόμενος διῃρῆσθαι καὶ τὸ συγκείμενον συγκεῖσθαι, ἔψευσται δὲ ὁ ἐναντίως [5] ἔχων ἢ τὰ πράγματα, πότ᾽ ἔστιν ἢ οὐκ ἔστι τὸ ἀληθὲς λεγόμενον ἢ ψεῦδος; τοῦτο γὰρ σκεπτέον τί λέγομεν. οὐ γὰρ διὰ τὸ ἡμᾶς οἴεσθαι ἀληθῶς σε λευκὸν εἶναι εἶ σὺ λευκός, ἀλλὰ διὰ τὸ σὲ εἶναι λευκὸν ἡμεῖς οἱ φάντες τοῦτο ἀληθεύομεν.	807. And in things this consists in being combined or being separated. Hence he who thinks that what is separated is separated, and that what is combined is combined, is right; but he who thinks about things otherwise than as they are, is wrong. And it is necessary to consider what we mean when we say that truth and falsity exist or do not exist. For it is not because we are right in thinking that you are white that you are white, but it is because you are white that in saying this we speak the truth.
εἰ δὴ τὰ μὲν ἀεὶ σύγκειται καὶ ἀδύνατα διαιρεθῆναι, [10] τὰ δ᾽ ἀεὶ διῄρηται καὶ ἀδύνατα συντεθῆναι, τὰ δ᾽ ἐνδέχεται τἀναντία, τὸ μὲν εἶναί ἐστι τὸ συγκεῖσθαι καὶ ἓν εἶναι, τὸ δὲ μὴ εἶναι τὸ μὴ συγκεῖσθαι ἀλλὰ πλείω εἶναι: περὶ μὲν οὖν τὰ ἐνδεχόμενα ἡ αὐτὴ γίγνεται ψευδὴς καὶ ἀληθὴς δόξα καὶ ὁ λόγος ὁ αὐτός, καὶ ἐνδέχεται ὁτὲ [15] μὲν ἀληθεύειν ὁτὲ δὲ ψεύδεσθαι: περὶ δὲ τὰ ἀδύνατα ἄλλως ἔχειν οὐ γίγνεται ὁτὲ μὲν ἀληθὲς ὁτὲ δὲ ψεῦδος, ἀλλ᾽ ἀεὶ ταὐτὰ ἀληθῆ καὶ ψευδῆ.	808. Therefore, if some things are always combined and it is impossible for them to be separated, and others are always separated and it is impossible for them to be combined, and others admit of both contraries, then being consists in being combined and being one, and non-being consists in not being combined and being many. Therefore with regard to contingent things the same opinion or statement becomes true and false, and it is possible for it at one time to be true and at another to be false. But with regard to those things which are incapable of being otherwise than as they are, an opinion is not sometimes true and sometimes false, but one. is always true and the other always false.
περὶ δὲ δὴ τὰ ἀσύνθετα τί τὸ εἶναι ἢ μὴ εἶναι καὶ τὸ ἀληθὲς καὶ τὸ ψεῦδος; οὐ γάρ ἐστι σύνθετον, ὥστε εἶναι μὲν ὅταν συγκέηται, μὴ εἶναι δὲ [20] ἐὰν διῃρημένον ᾖ, ὥσπερ τὸ λευκὸν <�τὸ> ξύλον ἢ τὸ ἀσύμμετρον [21] τὴν διάμετρον: οὐδὲ τὸ ἀληθὲς καὶ τὸ ψεῦδος ὁμοίως ἔτι ὑπάρξει καὶ ἐπ᾽ ἐκείνων. ἢ ὥσπερ οὐδὲ τὸ ἀληθὲς ἐπὶ τούτων τὸ αὐτό, οὕτως οὐδὲ τὸ εἶναι,	809. However, with regard to things which are not composite, what is being and non-being, and what is truth and falsity? For such things are not composite so as to exist when combined and not exist when separated; for example, the proposition “The wood is white,” or the proposition “The diagonal is incommensurable.” Nor will truth and falsity still be present in them in the same way as in other things. And just as truth is not the same in these things, in a similar fashion neither is being the same.
ἀλλ᾽ ἔστι τὸ μὲν ἀληθὲς ἢ ψεῦδος, τὸ μὲν θιγεῖν καὶ φάναι ἀληθές (οὐ γὰρ ταὐτὸ κατάφασις [25] καὶ φάσις), τὸ δ᾽ ἀγνοεῖν μὴ θιγγάνειν (ἀπατηθῆναι γὰρ περὶ τὸ τί ἐστιν οὐκ ἔστιν ἀλλ᾽ ἢ κατὰ συμβεβηκός: ὁμοίως δὲ καὶ περὶ τὰς μὴ συνθετὰς οὐσίας, οὐ γὰρ ἔστιν ἀπατηθῆναι:	810. But truth or falsity is as follows: to come in contact with a thing and to express it is truth (for expression is not the same as affirmation), and not to come in contact with a thing is ignorance. For it is impossible to be deceived about a thing’s quiddity, except in an accidental sense; and the same holds true in the case of incomposite things, for it is impossible to be deceived about them.
καὶ πᾶσαι εἰσὶν ἐνεργείᾳ, οὐ δυνάμει, ἐγίγνοντο γὰρ ἂν καὶ ἐφθείροντο, νῦν δὲ τὸ ὂν αὐτὸ οὐ γίγνεται οὐδὲ φθείρεται, [30] ἔκ τινος γὰρ ἂν ἐγίγνετο: ὅσα δή ἐστιν ὅπερ εἶναί τι καὶ ἐνέργειαι, περὶ ταῦτα οὐκ ἔστιν ἀπατηθῆναι ἀλλ᾽ ἢ νοεῖν ἢ μή: ἀλλὰ τὸ τί ἐστι ζητεῖται περὶ αὐτῶν, εἰ τοιαῦτά ἐστιν ἢ μή):	811. And they are all actual and not potential, for otherwise they would be generated and corrupted. But being itself is neither generated nor corrupted; otherwise it would be generated out of something. Therefore, regarding all those things which are really quiddities and actualities, it is impossible to be deceived about them, but one must either know them or not. But concerning them we may ask what they are, namely, whether they are such and such or not.
τὸ δὲ εἶναι ὡς τὸ ἀληθές, καὶ τὸ μὴ εἶναι τὸ ὡς τὸ ψεῦδος, ἓν μέν ἐστιν, εἰ σύγκειται, ἀληθές, τὸ [35] δ᾽ εἰ μὴ σύγκειται, ψεῦδος: τὸ δὲ ἕν, εἴπερ ὄν, οὕτως ἐστίν, εἰ δὲ μὴ οὕτως, οὐκ ἔστιν: [1052α] [1] τὸ δὲ ἀληθὲς τὸ νοεῖν ταῦτα: τὸ δὲ ψεῦδος οὐκ ἔστιν, οὐδὲ ἀπάτη, ἀλλὰ ἄγνοια, οὐχ οἵα ἡ τυφλότης: ἡ μὲν γὰρ τυφλότης ἐστὶν ὡς ἂν εἰ τὸ νοητικὸν ὅλως μὴ ἔχοι τις.	812. Now considering being in the sense of truth and non-being in the sense of falsity, in the case of composite beings there is truth if the thing is combined with the attribute attributed to it; in the case of simple beings the thing is just simply so. And if a thing is truly a being, it is so in some particular way; but if it is not, it does not exist at all. Again, truth means to know these beings, and there is neither falsity nor deception about them but only ignorance; but not ignorance such as blindness is, for blindness is as if one did not have intellective power at all.
φανερὸν δὲ καὶ ὅτι περὶ τῶν ἀκινήτων [5] οὐκ ἔστιν ἀπάτη κατὰ τὸ ποτέ, εἴ τις ὑπολαμβάνει ἀκίνητα. οἷον τὸ τρίγωνον εἰ μὴ μεταβάλλειν οἴεται, οὐκ οἰήσεται ποτὲ μὲν δύο ὀρθὰς ἔχειν ποτὲ δὲ οὔ (μεταβάλλοι γὰρ ἄν), ἀλλὰ τὶ μὲν τὶ δ᾽ οὔ, οἷον ἄρτιον ἀριθμὸν πρῶτον εἶναι μηθένα, ἢ τινὰς μὲν τινὰς δ᾽ οὔ: ἀριθμῷ δὲ περὶ ἕνα οὐδὲ [10] τοῦτο: οὐ γὰρ ἔτι τινὰ μὲν τινὰ δὲ οὒ οἰήσεται, ἀλλ᾽ ἀληθεύσει ἢ ψεύσεται ὡς ἀεὶ οὕτως ἔχοντος.	813. And concerning immobile things it is also evident that there is no deception about them as regards time, if one assumes that they are immobile. For example, if one assumes that a triangle does not change, he will not be of the opinion that at one time its angles are equal to two right angles and that at another time they are not; for otherwise it would change. But he might assume that one thing has such and such a property and that another has not; for example, one might assume that no even number is a prime number, or that some are and some are not. But this is impossible as regards one single number; for one will not assume that one thing is such and another is not; but whether he speaks truly or falsely, a thing is always disposed in the same way.