Μετέχετον μὴν ἄμφω (κίνησις καὶ στάσις) ταὐτοῦ καὶ θατέρου.…
Μὴ τοίνυν λέγωμεν κίνησιν γ’ εἶναι ταὐτὸν ἢ θάτερον, μηδ’ αὖ στάσιν. He had before said — Ἀλλ’ οὔ τι μὴν κίνησίς γε καὶ στάσις οὐθ’ ἕτερον οὔτε ταὐτόν ἐστιν (p. 255 A).
Plato here says, It is true that κίνησις μετέχει ταὐτοῦ, but it is not true that κίνησίς ἐστι ταὐτόν. Again, p. 259 A. τὸ μὲν ἕτερον μετασχὸν τοῦ ὄντος ἔστι μὲν διὰ ταύτην τὴν μέθεξιν, οὐ μὴν ἐκεῖνό γε οὖ μετέσχεν ἀλλ’ ἕτερον. He understands, therefore, that ἐστι, when used as copula, implies identity between the predicate and the subject.
This is the same point of view from which Antisthenes looked, when he denied the propriety of saying Ἄνθρωπός ἐστιν ἀγαθός — Ἄνθρωπός ἐστι κακός: and when he admitted only identical propositions, such as Ἄνθρωπός ἐστιν ἄνθρωπος — Ἄγαθός ἐστιν ἀγαθός. He assumed that ἐστι, when intervening between the subject and the predicate, implies identity between them; and the same assumption is made by Plato in the passage now before us. Whether Antisthenes would have allowed the proposition — Ἄνθρωπος μετέχει κακίας, or other propositions in which ἐστι does not appear as copula, we do not know enough of his opinions to say.
Compare Aristotel. Physic. i. 2, 185, b. 27, with the Scholia of Simplikius, p. 330, a. 331, b. 18-28, ed. Brandis.
Some things are always named or spoken of per se, others with reference to something else. Thus, Diversum is always different from something else: it is relative, implying a correlate.[114] In this, as well as in other points, Diversum (or Different) is a distinct Form, Genus, or Idea, which runs through all other things whatever. Each thing is different from every other thing: but it differs from them, not through any thing in its own nature, but because it partakes of the Form or Idea of Diversum or the Different.[115] So, in like manner, the Form or Idea of Idem (or Same) runs through all other things: since each thing is both different from all others, and is also the same with itself.
[114] Plato, Sophist. p. 255 C-D. τῶν ὄντων τὰ μὲν αὐτὰ καθ’ αὑτά, τά δὲ πρὸς ἄλληλα ἀεὶ λέγεσθαι . . . Τὸ δ’ ἕτερον ἀεὶ πρὸς ἕτερον . . . Νῦν δὲ ἀτεχνῶς ἡμῖν ὅ, τι περ ἂν ἕτερον ᾖ, συμβέβηκεν ἐξ ἀνάγκης ἑτέρου τοῦτο ὅπερ ἐστὶν εἶναι. These last words partly anticipate Aristotle’s explanation of τὰ πρός τι (Categor. p. 6, a. 38).
Here we have, for the first time so far as I know (certainly anterior to Aristotle), names relative and non-relative, distinguished as classes, and contrasted with each other. It is to be observed that Plato here uses λέγεσθαι and εἶναι as equivalent; which is not very consistent with the sense which he assigns to ἐστιν in predication: see the [note] immediately preceding.
[115] Plato, Sophist. p. 255 E. πέμπτον δὴ τὴν θατέρου φύσιν λεκτέον ἐν τοῖς εἴδεσιν οὖσαν, ἐν οἷς προαιρούμεθα … καὶ διὰ πάντων γε αὐτὴν αὐτῶν φήσομεν εἶναι διεληλυθυῖαν· ἓν ἕκαστον γὰρ ἕτερον εἶναι τῶν ἄλλων οὐ διὰ τὴν αὑτοῦ φύσιν, ἀλλὰ διὰ τὸ μετέχειν τῆς ἰδέας τῆς θατέρου.