When Is A Story A Soundtrack?

There's music in movie soundtracks, of course. But there's music too in words, easy to hear if the words are poetry, and still there in sentences and stories; in the flow, internal rhyme, the lilting rhythm and cadences of speech; and old-fashioned storytelling around the fire. Those first storytellers, memorizing their lines, must surely have heard them to music in their minds--that's why they turned so many tales into song. But what about the written word? I wonder sometimes if those first...