This extract is from The Republic by Plato, Book III (398-403).
Then now, my friend, I said, that part of music or literary education which relates to the story or myth may be considered to be finished; for the matter and manner have both been discussed.
I think so too, he said.
Next in order will follow melody and song.
That is obvious.
Everyone now would be able to discover what we ought to say about them, if we are to be consistent with ourselves.
I fear, said Glaucon, laughing, that the word “everyone” hardly includes me, for I cannot at the moment say what they should be, though I have a suspicion.
At any rate you are aware that a song or ode has three parts – the words, the melody and the rhythm.
Yes, he said; so as that I know.
And as for the words, there will surely be no difference between words which are and which are not set to music; both will conform to the same laws, and these have already been determined by us?
And the melody and rhythm will be in conformity with the words?
We were saying, when we spoke of the subject-matter, that we had .....