The implication here seems to be that only a good person can be in tune with his words.
"LACHES: I’m very single-minded, Nicias, when it comes to discussions, or if you like, I’m not so much single-minded as in two minds about them. Sometimes you’d think I was fond of discussions, but on other occasions it would look as though I hated them. You see, whenever I hear a man talking about goodness or any kind of wisdom — a real man, that is, who lives by his principles — I’m overjoyed, because I can see that the speaker is in tune with his words and that the two go together. Such a man really is, I think, a true musician: he uses the finest mode and has tuned to it not just a lyre or some other entertaining instrument, but he has tuned his own life so that his words harmonize with his actions; and it’s done fairly and squarely in the Dorian mode, the one native mode of Greece, not in the Ionian or, I’ll warrant, in the Phrygian or Lydian modes either. In any event, a man like that fills me with pleasure when he speaks, and everyone would assume that I was fond of discussions — I’m so keen to take in what he has to say. But it pains me to hear someone who is quite the opposite, and the more eloquently he seems to speak, the worse it becomes, and then it looks as though I hate discussions. "
- Plato, Laches 188c-e
Kristian Zahrtmann: Socrates and Alcibiades, 1911. National Gallery of Denmark
‘Then the person who knows about music will be in love with those of his fellow-humans who are most like that; if someone were out of tune, he wouldn’t be in love with him.’
"SOCRATES: Now if there was someone who loved Alcibiades’ body, he wouldn’t be loving Alcibiades, only something that belonged to Alcibiades.
ALCIBIADES: That’s right.
SOCRATES: But someone who loved you would love your soul.
ALCIBIADES: By our argument, I think he’d have to.
SOCRATES: Wouldn’t someone who loves your body go off and leave you when your beauty is no longer in full bloom?
ALCIBIADES: Obviously.
SOCRATES: But someone who loves your soul will not leave you, as long as you’re making progress.
ALCIBIADES: That’s probably right.
SOCRATES: Well, I’m the one who won’t leave you—I’m the one who will stay with you, now that your body has lost its bloom and everyone else has gone away.
ALCIBIADES: I’m glad you are, Socrates, and I hope you never leave me.
SOCRATES: Then you must try to be as attractive as possible."
‘Then the person who knows about music will be in love with those of his fellow-humans who are most like that; if someone were out of tune, he wouldn’t be in love with him.’
- Plato, Republic 402d
"SOCRATES: Now if there was someone who loved Alcibiades’ body, he wouldn’t be loving Alcibiades, only something that belonged to Alcibiades.
ALCIBIADES: That’s right.
SOCRATES: But someone who loved you would love your soul.
ALCIBIADES: By our argument, I think he’d have to.
SOCRATES: Wouldn’t someone who loves your body go off and leave you when your beauty is no longer in full bloom?
ALCIBIADES: Obviously.
SOCRATES: But someone who loves your soul will not leave you, as long as you’re making progress.
ALCIBIADES: That’s probably right.
SOCRATES: Well, I’m the one who won’t leave you—I’m the one who will stay with you, now that your body has lost its bloom and everyone else has gone away.
ALCIBIADES: I’m glad you are, Socrates, and I hope you never leave me.
SOCRATES: Then you must try to be as attractive as possible."
- Socrates in Plato's "Alcibiades", 131c-131d