The Nether Sun

A hollow world with a small sun in the middle: the land curves up and hangs overhead, rivers and all. It is the one place on the three roads where you can breathe without a suit. Firemoss grows toward the sun; among the hills lie the ribs of giants, and at the start of the world there is a great hearth. The sun flares every few minutes: the sky whitens, a line counts the seconds — get under a firemoss crown or a rock: the open ground burns. Where flares have scorched the moss away, suncoal lies bare: one piece burns in a furnace as long as a bucket of lava.