§2.5#1Διωρισμένων δὲ τούτων λέγωμεν κοινῇ περὶ πάσης αἰσθήσεως.
Now that these things have been defined, let us speak in general about all sensation.
ἡ δʼ αἴσθησις ἐν τῷ κινεῖσθαί τε καὶ πάσχειν συμβαίνει, καθάπερ εἴρηται· δοκεῖ γὰρ ἀλλοίωσίς τις εἶναι.
Sensation, as has been said, occurs in being moved and undergoing an effect; for it seems to be a certain kind of alteration.
φασὶ δέ τινες καὶ τὸ ὅμοιον ὑπὸ τοῦ ὁμοίου πάσχειν.
And some say that like undergoes an effect by like.
τοῦτο δὲ πῶς δυνατὸν ἢ ἀδύνατον, εἰρήκαμεν ἐν τοῖς καθόλου λόγοις περὶ τοῦ ποιεῖν καὶ πάσχειν.
But how this is possible or impossible, we have said in our general treatises on acting and undergoing.
ἔχει δʼ ἀπορίαν διὰ τί καὶ τῶν αἰσθήσεων αὐτῶν οὐ γίνεται αἴσθησις, καὶ διὰ τί ἄνευ τῶν ἔξω οὐ ποιοῦσιν αἴσθησιν, ἐνόντος πυρὸς καὶ γῆς καὶ τῶν ἄλλων στοιχείων, ὧν ἐστὶν ἡ αἴσθησις καθʼ αὑτὰ ἢ τὰ συμβεβηκότα τούτοις.
And it presents a difficulty why sensation of the senses themselves does not occur, and why they do not produce sensation without external objects, although fire and earth and the other elements are present within, of which there is sensation either in themselves or in their accidents.
δῆλον οὖν ὅτι τὸ αἰσθητικὸν οὐκ ἔστιν ἐνεργείᾳ, ἀλλὰ δυνάμει μόνον, διὸ οὐκ αἰσθάνεται, καθάπερ τὸ καυστὸν οὐ καίεται αὐτὸ καθʼ αὑτὸ ἄνευ τοῦ καυστικοῦ· ἔκαιε γὰρ ἂν ἑαυτό, καὶ οὐθὲν ἐδεῖτο τοῦ ἐντελεχείᾳ πυρὸς ὄντος.
It is clear, then, that the sensitive is not in activity, but in potentiality only; wherefore it does not sense, just as the combustible does not burn by itself without that which is capable of burning it; for otherwise it would have burned itself, and would have had no need of that which is fire in actuality.
ἐπειδὴ δὲ τὸ αἰσθάνεσθαι λέγομεν διχῶς (τό τε γὰρ δυνάμει ἀκοῦον καὶ ὁρῶν ἀκούειν καὶ ὁρᾶν λέγομεν, κἂν τύχῃ καθεῦδον, καὶ τὸ ἤδη ἐνεργοῦν), διχῶς ἂν λέγοιτο καὶ ἡ αἴσθησις, ἡ μὲν ὡς δυνάμει, ἡ δὲ ὡς ἐνεργείᾳ.
And since we speak of sensing in two ways (for we say that that which hears and sees potentially hears and sees, even if it happens to be asleep, as well as that which is already active), sensation also would be spoken of in two ways, the one as potential, the other as active.
ὁμοίως δὲ καὶ τὸ αἰσθητόν, τό τε δυνάμει ὂν καὶ τὸ ἐνεργείᾳ.
And likewise also the sensible, both that which is potentially and that which is actively.
πρῶτον μὲν οὖν ὡς τοῦ αὐτοῦ ὄντος τοῦ πάσχειν καὶ τοῦ κινεῖσθαι καὶ τοῦ ἐνεργεῖν λέγωμεν· καὶ γὰρ ἔστιν ἡ κίνησις ἐνέργειά τις, ἀτελὴς μέντοι, καθάπερ ἐν ἑτέροις εἴρηται.
First, then, let us speak on the assumption that undergoing, being moved, and acting are the same thing; for motion is indeed a certain activity, although incomplete, as has been said in other places.
πάντα δὲ πάσχει καὶ κινεῖται ὑπὸ τοῦ ποιητικοῦ καὶ ἐνεργείᾳ ὄντος.
And everything undergoes and is moved by that which is productive and exists in activity.
διὸ ἔστι μὲν ὡς ὑπὸ τοῦ ὁμοίου πάσχει, ἔστι δὲ ὡς ὑπὸ τοῦ ἀνομοίου, καθάπερ εἴπομεν· πάσχει μὲν γὰρ τὸ ἀνόμοιον, πεπονθὸς δʼ ὅμοιόν ἐστιν.
Wherefore, in one way it undergoes by the like, and in another way by the unlike, as we said; for the unlike undergoes, but having undergone, it is like.
διαιρετέον δὲ καὶ περὶ δυνάμεως καὶ ἐντελεχείας· νῦν γὰρ ἁπλῶς ἐλέγομεν περὶ αὐτῶν.
And we must also distinguish concerning potentiality and actuality; for now we have been speaking of them simply.
ἔστι μὲν γὰρ οὕτως ἐπιστῆμόν τι ὡς ἂν εἴποιμεν ἄνθρωπον ἐπιστήμονα ὅτι ὁ ἄνθρωπος τῶν ἐπιστημόνων καὶ ἐχόντων ἐπιστήμην· ἔστι δʼ ὡς ἤδη λέγομεν ἐπιστήμονα τὸν ἔχοντα τὴν γραμματικήν (ἑκάτερος δὲ τούτων οὐ τὸν αὐτὸν τρόπον δυνατός ἐστιν, ἀλλʼ ὁ μὲν ὅτι τὸ γένος τοιοῦτον καὶ ἡ ὕλη, ὁ δʼ ὅτι βουληθεὶς δυνατὸς θεωρεῖν, ἂν μή τι κωλύσῃ τῶν ἔξωθεν)·
For there is something that is knowing in such a way as we would say that a man is knowing because man is among those who know and have knowledge; and there is that which we already call knowing as having grammar, (but each of these is potential not in the same way, but the former because the genus and the matter is of such a kind, the latter because, if he wishes, he is capable of contemplating, unless something from without prevents); and there is he who is already contemplating, being in actuality and knowing in the proper sense "this A".
ὁ δʼ ἤδη θεωρῶν, ἐντελεχείᾳ ὢν καὶ κυρίως ἐπιστάμενος τόδε τὸ Α. ἀμφότεροι μὲν οὖν οἱ πρῶτοι, κατὰ δύναμιν ἐπιστήμονες ὄντες, ἐνεργείᾳ γίνονται ἐπιστήμονες, ἀλλʼ ὁ μὲν διὰ μαθήσεως ἀλλοιωθεὶς καὶ πολλάκις ἐξ ἐναντίας μεταβαλὼν ἕξεως, ὁ δʼ ἐκ τοῦ ἔχειν
Both of the first, then, being knowing potentially, become knowing in activity, but the one by being altered through learning and often changing from an opposite state, the other from having...