Plato on Why Opposites Attract (Plato, Lysis 215c-d)

“I once heard someone saying—and I just now remembered it—that like is most hostile to like and the good is hostile to the good. Indeed, I believe that he furnished Hesiod as a witness, since he says that “a potter rivals a potter, a singer a singer, and a beggar a beggar” and he says that this is the same by necessity with everything else, especially when something is very similar, they are filled with envy, competitiveness, and enmity. But things that are unlike one another are filled with love.”

῎Ηδη ποτέ του ἤκουσα λέγοντος, καὶ ἄρτι ἀναμιμνῄσκομαι, ὅτι τὸ μὲν ὅμοιον τῷ ὁμοίῳ καὶ οἱ ἀγαθοὶ τοῖς ἀγαθοῖς πολεμιώτατοι εἶεν· καὶ δὴ καὶ τὸν ῾Ησίοδον ἐπήγετο μάρτυρα, λέγων ὡς ἄρα—

καὶ κεραμεὺς κεραμεῖ κοτέει καὶ ἀοιδὸς ἀοιδῷ
καὶ πτωχὸς πτωχῷ,

καὶ τἆλλα δὴ πάντα οὕτως ἔφη ἀναγκαῖον εἶναι μάλιστα τὰ ὁμοιότατα ἄλληλα φθόνου τε καὶ φιλονικίας καὶ ἔχθρας ἐμπίμπλασθαι, τὰ δ’ ἀνομοιότατα φιλίας·

I am not quite sure that Hesiod would agree to this interpretation:

Hes. Fr. 264

“Good men flock to the tables of good men on their own.”
αὐτόματοι δ’ ἀγαθοὶ ἀγαθῶν ἐπὶ δαῖτας ἵενται.

And, because of my age, I cannot even think “opposites attract” without hearing this: