§11Ἐναντίον δέ ἐστιν ἐξ ἀνάγκης ἀγαθῷ μὲν κακόν· τοῦτο δὲ δῆλον τῇ καθ᾿ ἕκαστον ἐπαγωγῇ, οἷον ὑγιείᾳ νόσος καὶ ἀνδρείᾳ δειλία, ὁμοίως δὲ καὶ ἐπὶ τῶν ἄλλων.
To a good thing, a bad thing is of necessity contrary; and this is clear from induction in particular cases, for example, sickness to health and cowardice to courage, and likewise also in the case of the others.
Κακῷ δὲ ὁτὲ μὲν ἀγαθὸν ἐναντίον, ὁτὲ δὲ κακόν· τῇ γὰρ ἐνδείᾳ κακῷ ὄντι ἡ ὑπερβολὴ ἐναντίον κακὸν ὄν· ὁμοίως δὲ καὶ ἡ μεσότης ἐναντία ἑκατέρῳ, οὖσα ἀγαθόν.
But to a bad thing, sometimes a good thing is contrary, and sometimes a bad thing; for to deficiency, which is a bad thing, excess is contrary, which is also a bad thing; and likewise the mean is contrary to each, which is a good thing.
Ἐπ᾿ ὀλίγων δ᾿ ἂν τὸ τοιοῦτον ἴδοι τις, ἐπὶ δὲ τῶν πλείστων ἀεὶ τῷ κακῷ τὸ ἀγαθὸν ἐναντίον ἐστίν.
But one would see such a thing in few cases, while in most cases the good is always contrary to the bad.
Ἔτι ἐπὶ τῶν ἐναντίων οὐκ ἀναγκαῖον, ἐὰν θάτερον ᾖ, καὶ τὸ λοιπὸν εἶναι.
Furthermore, in the case of contraries, it is not necessary that if the one exists, the other also exists.
Ὑγιαινόντων μὲν γὰρ ἁπάντων ὑγίεια μὲν ἔσται, νόσος δὲ οὔ· ὁμοίως δὲ καὶ λευκῶν ὄντων ἁπάντων λευκότης μὲν ἔσται, μελανία δὲ οὔ.
For if everyone is healthy, health will exist, but sickness will not; and likewise also if all things are white, whiteness will exist, but blackness will not.
Ἔτι εἰ τὸ Σωκράτην ὑγιαίνειν τῷ Σωκράτην νοσεῖν ἐναντίον ἐστί, μὴ ἐνδέχεται δὲ ἅμα ἀμφότερα τῷ αὐτῷ ὑπάρχειν, οὐκ ἂν ἐνδέχοιτο τοῦ ἑτέρου τῶν ἐναντίων ὄντος καὶ τὸ λοιπὸν εἶναι· ὄντος γὰρ τοῦ Σωκράτην ὑγιαίνειν οὐκ ἂν εἴη τὸ νοσεῖν Σωκράτην.
Again, if Socrates being healthy is contrary to Socrates being sick, and it is not possible for both to belong to the same thing at the same time, it would not be possible for the other of the contraries to exist when the one exists; for when Socrates being healthy exists, Socrates being sick would not exist.
Δῆλον δὲ ὅτι καὶ περὶ ταὐτὸν ἢ εἴδει ἢ γένει πέφυκε γίνεσθαι τὰ ἐναντία.
It is also clear that contraries are by nature apt to occur about that which is the same either in species or in genus.
Νόσος μὲν γὰρ καὶ ὑγίεια ἐν σώματι ζῴου πέφυκε γίνεσθαι, λευκότης δὲ καὶ μελανία ἁπλῶς ἐν σώματι, δικαιοσύνη δὲ καὶ ἀδικία ἐν ψυχῇ ἀνθρώπου.
For sickness and health are by nature apt to occur in the body of an animal, but whiteness and blackness simply in a body, and justice and injustice in the soul of a human.
Ἀνάγκη δὲ πάντα τὰ ἐναντία ἢ ἐν τῷ αὐτῷ γένει εἶναι ἢ ἐν τοῖς ἐναντίοις γένεσιν, ἢ αὐτὰ γένη εἶναι.
And it is necessary for all contraries either to be in the same genus, or in contrary genera, or to be themselves genera.
Λευκὸν μὲν γὰρ καὶ μέλαν ἐν τῷ αὐτῷ γένει (χρῶμα γὰρ αὐτῶν τὸ γένος), δικαιοσύνη δὲ καὶ ἀδικία ἐν τοῖς ἐναντίοις γένεσιν (τοῦ μὲν γὰρ ἀρετή, τοῦ δὲ κακία τὸ γένος)· ἀγαθὸν δὲ καὶ κακὸν οὐκ ἔστιν ἐν γένει, ἀλλ᾿ αὐτὰ τυγχάνει γένη τινῶν ὄντα.
For white and black are in the same genus (for color is their genus), but justice and injustice are in contrary genera (for virtue is the genus of the one, and vice of the other); while good and bad are not in a genus, but themselves happen to be genera of certain things.