When reading Greek philosophy, I think it is best to read the primary source first rather than about it – unless you are going to take an exam then you probably need to know how others have interpreted it. However if you are reading for pleasure or your own personal fulfilment then you get the satisfaction of understanding for yourself and if you haven’t understood exactly right it will have set off trains of thoughts and ideas in your head that let you look at the world through a new perspective. Here Stilpo has raised a problem that is not easy to resolve.
This is from Plutarch against Colotes (Section 23) with the translation from the Perseus site.
But as for Stilpo, thus his argument stands. ‘If of a man we predicate good, and of an horse running, the predicate or thing predicated is not the same with the subject or that of which it is predicated, but the essential definition of man is one, and of good another. And again, to be a horse differs from to be running. For being asked the definition of the one and of the other, we do not give the same for them both; and therefore those err who predicate the one of the other. For if good is the same with man, and to run the same with a horse, how is good affirmed also of food and medicine, and again (by Jupiter) to run of a lion and a dog? But if the predicate is different, then we do not rightly say that a man is good, and a horse runs
οὐ μὴν ἀλλὰ τὸ ἐπὶ τοῦ Στίλπωνος τοιοῦτόν ἐστιν˙ εἰ περὶ ἵππου τὸ τρέχειν κατηγοροῦμεν, οὔ φησι ταὐτὸν εἶναι τῷ περὶ οὗ κατηγορεῖται τὸ κατηγορούμενον ἀλλ’ ἕτερον˙ 〈οὐδ’ εἰ περὶ ἀνθρώπου τὸ ἀγαθὸν εἶναι, ἀλλ’ ἕτερον〉 μὲν ἀνθρώπῳ τοῦ τί ἦν εἶναι τὸν λόγον, ἕτερον δὲ τῷ ἀγαθῷ˙ καὶ πάλιν τὸ ἵππον εἶναι τοῦ τρέχοντα εἶναι διαφέρειν˙ ἑκατέρου γὰρ ἀπαιτούμενοι τὸν λόγον οὐ τὸν αὐτὸν ἀποδίδομεν ὑπὲρ ἀμφοῖν. ὅθεν ἁμαρτάνειν τοὺς ἕτερον ἑτέρου κατηγοροῦντας [. . . .] εἰ μὲν γὰρ ταὐτόν ἐστι τῷ ἀνθρώπῳ τὸ ἀγαθὸν καὶ τῷ ἵππῳ τὸ τρέχειν, πῶς καὶ (β) σιτίου καὶ φαρμάκου τὸ ἀγαθὸν καὶ νὴ Δία πάλιν λέοντος καὶ κυνὸς τὸ τρέχειν κατηγοροῦμεν; 〈εἰ〉 δ’ ἕτερον, οὐκ ὀρθῶς ἄνθρωπον ἀγαθὸν καὶ ἵππον τρέχειν λέγομεν.