§7.15ἐπεὶ δʼ ἡ οὐσία ἑτέρα, τό τε σύνολον καὶ ὁ λόγος (λέγω δʼ ὅτι ἡ μὲν οὕτως ἐστὶν οὐσία, σὺν τῇ ὕλῃ συνειλημμένος ὁ λόγος, ἡ δʼ ὁ λόγος ὅλως), ὅσαι μὲν οὖν οὕτω λέγονται, τούτων μὲν ἔστι φθορά (καὶ γὰρ γένεσις), τοῦ δὲ λόγου οὐκ ἔστιν οὕτως ὥστε φθείρεσθαι (οὐδὲ γὰρ γένεσις, οὐ γὰρ γίγνεται τὸ οἰκίᾳ εἶναι ἀλλὰ τὸ τῇδε τῇ οἰκίᾳ), ἀλλʼ ἄνευ γενέσεως καὶ φθορᾶς εἰσὶ καὶ οὐκ εἰσίν· δέδεικται γὰρ ὅτι οὐδεὶς ταῦτα γεννᾷ οὐδὲ ποιεῖ.
But since substance is twofold, both the concrete whole and the formula (I mean that one kind of substance is the formula taken with the matter, while the other is the formula in its entirety), in the case of those substances which are so called in the former sense, there is destruction (for there is also generation), but of the formula there is no destruction in such a way that it perishes (for there is no generation either; for 'being a house' does not come to be, but only 'being this particular house'), but without generation and destruction they exist and do not exist; for it has been shown that no one generates or makes them.
διὰ τοῦτο δὲ καὶ τῶν οὐσιῶν τῶν αἰσθητῶν τῶν καθʼ ἕκαστα οὔτε ὁρισμὸς οὔτε ἀπόδειξις ἔστιν, ὅτι ἔχουσιν ὕλην ἧς ἡ φύσις τοιαύτη ὥστʼ ἐνδέχεσθαι καὶ εἶναι καὶ μή· διὸ φθαρτὰ πάντα τὰ καθʼ ἕκαστα αὐτῶν.
And for this reason also, there is neither definition nor demonstration of individual sensible substances, because they have matter whose nature is such that it is capable of both being and not being; wherefore all individual things among them are perishable.
εἰ οὖν ἥ τʼ ἀπόδειξις τῶν ἀναγκαίων καὶ ὁ ὁρισμὸς ἐπιστημονικόν, καὶ οὐκ ἐνδέχεται, ὥσπερ οὐδʼ ἐπιστήμην ὁτὲ μὲν ἐπιστήμην ὁτὲ δʼ ἄγνοιαν εἶναι, ἀλλὰ δόξα τὸ τοιοῦτόν ἐστιν, οὕτως οὐδʼ ἀπόδειξιν οὐδʼ ὁρισμόν, ἀλλὰ δόξα ἐστὶ τοῦ ἐνδεχομένου ἄλλως ἔχειν, δῆλον ὅτι οὐκ ἂν εἴη αὐτῶν οὔτε ὁρισμὸς οὔτε ἀπόδειξις.
If, then, demonstration is of necessary things and definition is scientific, and it is not possible for knowledge to be at one time knowledge and at another time ignorance (for such a thing is opinion), and likewise there is neither demonstration nor definition of what is contingent, but opinion is of that which is capable of being otherwise, it is clear that there would be neither definition nor demonstration of them.
ἄδηλά τε γὰρ τὰ φθειρόμενα τοῖς ἔχουσι τὴν ἐπιστήμην, ὅταν ἐκ τῆς αἰσθήσεως ἀπέλθῃ, καὶ σωζομένων τῶν λόγων ἐν τῇ ψυχῇ τῶν αὐτῶν οὐκ ἔσται οὔτε ὁρισμὸς ἔτι οὔτε ἀπόδειξις.
For perishable things are obscure to those who have knowledge of them, when they depart from perception; and even though the same formulae remain preserved in the soul, there will no longer be either definition or demonstration of them.
διὸ δεῖ, τῶν πρὸς ὅρον ὅταν τις ὁρίζηταί τι τῶν καθʼ ἕκαστον, μὴ ἀγνοεῖν ὅτι ἀεὶ ἀναιρεῖν ἔστιν· οὐ γὰρ ἐνδέχεται ὁρίσασθαι.
Wherefore, when anyone defines any of the individual things, he must not be ignorant of the fact that it is always possible to refute his definition; for it is not possible to define them.
οὐδὲ δὴ ἰδέαν οὐδεμίαν ἔστιν ὁρίσασθαι.
Nor, indeed, is it possible to define any Idea.
τῶν γὰρ καθʼ ἕκαστον ἡ ἰδέα, ὡς φασί, καὶ χωριστή· ἀναγκαῖον δὲ ἐξ ὀνομάτων εἶναι τὸν λόγον, ὄνομα δʼ οὐ ποιήσει ὁ ὁριζόμενος (ἄγνωστον γὰρ ἔσται), τὰ δὲ κείμενα κοινὰ πᾶσιν· ἀνάγκη ἄρα ὑπάρχειν καὶ ἄλλῳ ταῦτα·
For the Idea is, as they say, an individual and separate; but the formula must of necessity consist of words, and the definer will not make a new word (for it will be unknown), and the existing words are common to all; therefore, these must also belong to something else.
οἷον εἴ τις σὲ ὁρίσαιτο, ζῷον ἐρεῖ ἰσχνὸν ἢ λευκὸν ἢ ἕτερόν τι ὃ καὶ ἄλλῳ ὑπάρξει.
For instance, if anyone should define you, he will say 'an animal that is thin' or 'white' or something else which will also belong to another.
εἰ δέ τις φαίη μηδὲν κωλύειν χωρὶς μὲν πάντα πολλοῖς ἅμα δὲ μόνῳ τούτῳ ὑπάρχειν, λεκτέον πρῶτον μὲν ὅτι καὶ ἀμφοῖν, οἷον τὸ ζῷον δίπουν τῷ ζῴῳ καὶ τῷ δίποδι (καὶ τοῦτο ἐπὶ μὲν τῶν ἀϊδίων καὶ ἀνάγκη εἶναι, πρότερά γʼ ὄντα καὶ μέρη τοῦ συνθέτου· ἀλλὰ μὴν καὶ χωριστά, εἴπερ τὸ ἄνθρωπος χωριστόν· ἢ γὰρ οὐθὲν ἢ ἄμφω· εἰ μὲν οὖν μηθέν, οὐκ ἔσται τὸ γένος παρὰ τὰ εἴδη, εἰ δʼ ἔσται, καὶ ἡ διαφορά)· εἶθʼ ὅτι πρότερα τῷ εἶναι· ταῦτα δὲ οὐκ ἀνταναιρεῖται.
But if anyone should say that nothing prevents all the elements from belonging separately to many but collectively to this one alone, we must say, first, that they also belong to both—for instance, 'two-footed animal' belongs to 'animal' and to 'two-footed' (and in the case of eternal things this is even necessary, since they are prior to and parts of the compound; and indeed they are also separate, if 'man' is separate; for either neither is or both are; if, then, neither is, the genus will not exist apart from the species, and if it does exist, the difference will also exist); and secondly, that they are prior in being; and these are not destroyed together with the compound.
ἔπειτα εἰ ἐξ ἰδεῶν αἱ ἰδέαι (ἁσυνθετώτερα γὰρ τὰ ἐξ ὧν), ἔτι ἐπὶ πολλῶν δεήσει κἀκεῖνα κατηγορεῖσθαι ἐξ ὧν ἡ ἰδέα, οἷον τὸ ζῷον καὶ τὸ δίπουν.
Next, if the Ideas are composed of Ideas (for the things from which they are composed are more simple), those things from which the Idea is composed, such as 'animal' and 'two-footed', will also have to be predicated of many things.
εἰ δὲ μή, πῶς γνωρισθήσεται;
If not, how will they be known?
ἔσται γὰρ ἰδέα τις ἣν ἀδύνατον ἐπὶ πλειόνων κατηγορῆσαι ἢ ἑνός.
For there will be some Idea which cannot be predicated of more than one thing.
οὐ δοκεῖ δέ, ἀλλὰ πᾶσα ἰδέα εἶναι μεθεκτή.
But this is not believed to be so, rather every Idea is held to be participable.
ὥσπερ οὖν εἴρηται, λανθάνει ὅτι ἀδύνατον ὁρίσασθαι ἐν τοῖς ἀϊδίοις, μάλιστα δὲ ὅσα μοναχά, οἷον ἥλιος ἢ σελήνη.
As, then, has been said, it escapes notice that it is impossible to define among eternal things, and especially those that are unique, such as the sun or the moon.
οὐ μόνον γὰρ διαμαρτάνουσι τῷ προστιθέναι τοιαῦτα ὧν ἀφαιρουμένων ἔτι ἔσται ἥλιος, ὥσπερ τὸ περὶ γῆν ἰὸν ἢ νυκτικρυφές (ἂν γὰρ στῇ ἢ φανῇ, οὐκέτι ἔσται ἥλιος· ἀλλʼ ἄτοπον εἰ μή· ὁ γὰρ ἥλιος οὐσίαν τινὰ σημαίνεi)· ἔτι ὅσα ἐπʼ ἄλλου ἐνδέχεται, οἷον ἐὰν ἕτερος γένηται τοιοῦτος, δῆλον ὅτι ἥλιος ἔσται· κοινὸς ἄρα ὁ λόγος· ἀλλʼ ἦν τῶν καθʼ ἕκαστα ὁ ἥλιος, ὥσπερ Κλέων ἢ Σωκράτης·
For they fail not only by adding such things as, if removed, the sun will still exist, such as 'going around the earth' or 'hidden by night' (for if it stands still or appears, it will no longer be the sun; but it is absurd if it is not so, since 'the sun' signifies a certain substance); but also because of those attributes which can belong to another, so that if another thing becomes such, it is clear that it will be the sun; therefore the formula is common; but the sun was an individual, like Cleon or Socrates.
ἐπεὶ διὰ τί οὐδεὶς ὅρον ἐκφέρει αὐτῶν ἰδέας;
After all, why does no one bring forward a definition of an Idea?
γένοιτο γὰρ ἂν δῆλον πειρωμένων ὅτι ἀληθὲς τὸ νῦν εἰρημένον.
For it would become clear to those who try that what has now been said is true.