Into this wild abyss, The womb of nature and perhaps her grave, Of neither sea, nor shore, nor air, nor fire, But all these in their pregnant causes mixed Confusedly, and which thus must ever fight, Unless the almighty maker them ordain His dark materials to create more worlds, Into this wild abyss the wary fiend Stood on the brink of hell and looked a while, Pondering his voyage...

—John Milton, Paradise Lost, Book II The Golden Compass forms the first part of a story in three volumes. The first volume is set in a universe like ours, but different in many ways. The second volume is set partly in the universe we know. The third volume will move between the universes.