From Philip Pullman’s introduction to Oxford World’s Classics edition of Paradise Lost.
The Story as a Poem
So I begin with sound. I read Paradise Lost not only with my eyes, but with my mouth. … And thus it was that I first heard lines like this. Satan is making his way across the wastes of hell towards the new world he intends to corrupt, and a complex and majestic image evokes his flight: [Book II, lines 636-43]
As when far off a fleet at sea descried
Hangs in the clouds, by equinoctial winds
Close sailing from Bengala, or the Isles
Of Ternate and Tidor, whence merchants bring
Their spicy drugs: they on the trading flood
Through the wide Ethiopian to the Cape
Ply stemming nightly toward the pole. So seemed
far off the flying fiend . . .
… To see these things and hear them most vividly, I found that I had to take the lines in my mouth and utter them aloud. A whisper will do; you don’t have to bellow it, and annoy the neighbours; but air has to pass across your tongue and through your lips. Your body has to be involved.