It's not a musical. It's a play with music -- albeit a lot of music.
[But, he says,] I listened to the Grieg and said, 'OK, that's great music' and never listened to it again. ... but they are not direct. I consciously decided what comes out, comes out.
But other than that, I go from the text and the rhythms of the words. The melody comes from that.
It's all ultimately in the service of the play. At any given moment, you've got to be telling the story.
It's about the play. Where does it need to be really spare? Where do you need to start to drive the tempo? You figure out the tempo of the scene and support it. Basically, it's how to keep the storytelling clear, how to support it and, ideally, enhance it.