This is a story about magic and where it goes and perhaps more importantly where it comes from and why, although it doesn't pretend to answer all or any of these questions.
It may, however, help to explain why Gandalf never got married and why Merlin was a man. Because this is also a story about sex, although probably not in the athletic, tumbling, count-the-legs-and-divide-by-two sense unless the characters get totally beyond the author's control. They might.
However, it is primarily a story about a world. Here it comes now. Watch closely, the special effects are quite expensive.
A bass note sounds. It is a deep, vibrating chord that hints that the brass section may break in at any moment with a fanfare for the cosmos, because the scene is the blackness of deep space with a few stars glittering like the dandruff on the shoulders of God.
Then it comes into view overhead, bigger than the biggest, most unpleasantly armed starcruiser in the imagination of a three-ring film-maker: a turtle, ten thousand miles long. It is Great A'Tuin, one of the rare astrochelonians from a universe where things are less as they are and more like people imagine them to be, and it carries on its meteor-pocked shell four giant elephants who bear on their enormous shoulders the great round wheel of the Discworld.
As the viewpoint swings around, the whole of the world can be seen by the light of its tiny orbiting sun. There are continents, archipelagos, seas, deserts, mountain ranges and even a tiny central ice cap. The inhabitants of this place, it is obvious, won't have any truck with global theories. Their world, bounded by an encircling ocean that falls forever into space in one long waterfall, is as round and flat as a geological pizza, although without the anchovies.
A world like that, which exists only because the gods enjoy a joke, must be a place where magic can survive. And sex too, of course.
He came walking through the thunderstorm and you could tell he was a wizard, partly because of the long cloak and careen staff but mainly because the raindrops were stopping several feet from his head, and steaming.
It was good thunderstorm country, up here in the Ramtop Mountains, a country of jagged peaks, dense forests and little river valleys so deep the daylight had no sooner reached the bottom than it was time to leave again. Ragged wisps of cloud clung to the lesser peaks below the mountain trail along which the wizard slithered and slid. A few slot-eyed goats watched him with mild interest. It doesn't take a lot to interest goats.
Sometimes he would stop and throw his heavy staff into the air. It always came down pointing the same way and the wizard would sigh, pick it up, and continue his squelchy progress.
The storm walked around the hills on legs of lightning, shouting and grumbling.
The wizard disappeared around the bend in the track and the goats went back to their damp grazing.
Until something else caused them to look up. They stiffened, their eyes widening, their nostrils flaring.
This was strange, because there was nothing on the path. But the goats still watched it pass by until it was out of sight.
There was a village tucked in a narrow valley between steep woods. It wasn't a large village, and wouldn't have shown up on a map of the mountains. It barely showed up on a map of the village.
It was, in fact, one of those places that exist merely so that people can have come from them. The universe is littered with them: hidden villages, windswept little towns under wide skies, isolated cabins on chilly mountains, whose only mark on history is to be the incredibly ordinary place where something extraordinary started to happen. Often there is no more than a little plaque to reveal that, against all ecological probability, someone very famous was born halfway up a wall.
Mist curled between the houses as the wizard crossed a narrow bridge over the swollen stream and made his way to the village smithy, although the two facts had nothing to do with one another. The mist would have curled anyway: it was experienced mist and had got curling down to a fine art.
The smithy was fairly crowded, of course. A smithy is one place where you can depend on finding a good fire and someone to talk to. Several villagers were lounging in the warm shadows but, as the wizard approached, they sat up expectantly and tried to look intelligent, generally with indifferent success.
The smith didn't feel the need to be quite so subservient. He nodded at the wizard, but it was a greeting between equals, or at least between equals as far as the smith was concerned. After all, any halfway competent blacksmith has more than a nodding acquaintance with magic, or at least likes to think he has.
The wizard bowed. A white cat that had been sleeping by the furnace woke up and watched him carefully.
“What is the name of this place, sir?” said the wizard.
The blacksmith shrugged.
“Bad Ass,” he said.
“Bad - ?”
“Ass,” repeated the blacksmith, his tone defying anyone to make something of it.
The wizard considered this.
“A name with a story behind it,” he said at last, “which were circumstances otherwise I would be pleased to hear. But I would like to speak to you, smith, about your son.”
“Which one?” said the smith, and the hangers-on sniggered. The wizard smiled.
“You have seven sons, do you not? And you yourself were an eighth son?”
The smith's face stiffened. He turned to the other villagers.