"That sounds very useful," he says, diplomatic but very sincere. It would probably be helpful, somewhere like here. If the thing got used to being in a spot where the sky existed.

"So, um!" He points straight up at those three brightest stars. "You see those three, a-and the lot of little ones coming off it like a tail? That's called the Harpoon. The story goes, a mighty hero wanted to bring the kingdom of the gods down to the earth, and so threw his weapon into the sky to drag it down. But the gods were so powerful that the hero couldn't bring his weapon down, and when night fell it turned into stars and was stuck on the side of the gods' kingdom forever."

He opens the book to the right page and shows Some the illustration, of a strong-looking man hurling a weapon at what looked like a castle suspended in a cloud. "If you follow the line of the Harpoon, though, it points north, so people still use it to navigate even now."