The place where the story happened was a world on the back of four elephants perched on the shell of a giant turtle. That's the advantage of space. It's big enough to hold, practically anything, and so, eventually, it does. People think that it is strange to have a turtle ten thousand miles long and an elephant more than, two thousand miles tall, which just shows that the human brain is ill-adapted for thinking and was probably originally designed for cooling the blood. It believes mere size is amazing. There's nothing amazing about size. Turtles are amazing, and elephants are quite astonishing. But the fact that there's a big turtle is far less amazing than the fact that there is a turtle anywhere. The reason for the story was a mix of many things. There was humanity's desire to do forbidden deeds merely because they were forbidden. There was its desire to find new horizons and kill the people who live beyond them. There were die mysterious scrolls. There was the cucumber. But mostly there was the knowledge that one day, quite soon, it would be all over. "Ah. well, life goes on," people say when someone dies. But from the point of view of the person who has just died, it doesn't. It's the universe that goes on. Just as die deceased was getting the hang of everything it's all whisked away, by illness or accident or, in one case, a cucumber. Why this has to be is one of the imponderables of life, in the face of which people either start to pray ... or become really, really angry. The beginning of the story happened tens of thousands of years ago, on a wild and stormy night, when a speck of flame came down the mountain at the centre of the world. It moved in dodges and jerks, as if the unseen person carrying it was sliding and falling from rock to rock. At one point the line became a streak of sparks, ending in a snowdrift at the bottom of a crevasse. But a hand thrust up through the snow held the smoking embers of the torch, and the wind, driven by the anger of the gods, and with a sense of humour of its own, whipped the flame back into life ... And, after that, it never died. The end of the story began high above the world, but got lower and lower as it circled down towards the ancient and modern city of Ankh-Morpork, where, it was said, anything could be bought and sold - and if they didn't have what you wanted they could steal it for you. Some of them could even dream it... The creature now seeking out a particular building below was a trained Pointless Albatross and, by the standards of the world, was not particularly unusual.* (*Compared to, say, the Republican Bees, who committeed rather than swarmed and tended to stay in the hive a lot.) It was, though, pointless. It spent its entire life in a series of lazy journeys between the Rim and the Huh, and where was the point in that? This one was more or less tame. Its beady mad eye spotted where, for reasons entirely beyond its comprehension, anchovies could be found. And someone would remove this uncomfortable cylinder from its leg. It seemed a pretty good deal to the albatross and from this it can be deduced that these albatrosses are, if not completely pointless, at least rather dumb. Not at all like humans, therefore. Flight has been been said to be one of the great dreams of Mankind. In fact it merely harks back to Man's ancestors, whose greatest dream was of falling off the branch. In any case, other great dreams of Mankind have included the one about being chased by huge boots with teeth. And no one says that one has to make sense. Three busy hours later Lord Vetinari, the Patrician of Ankh-Morpork, was standing in the main hall of Unseen University, and he was impressed.
The wizards, once they understood the urgency of a problem, and then had lunch, and argued about the pudding, could actually work quite fast. Their method of finding a solution, as far as the Patrician could see, was by creative hubbub. If the question was, What is the best spell for turning a book of poetry into a frog?", then the one tiling they would not do was look in any book with a title like Major Amphibian Spells in a Literary Environment: A Comparison. That would, somehow, be cheating. They would argue about it instead, standing around a blackboard, seizing the chalk from one another and rubbing out bits of what the current chalk-holder was writing before he'd finished the other end of the sentence. Somehow, though, it all seemed to work. Now something stood in the centre of the hall. It looked, to the arts- educated Patrician, like a big magnifying glass surrounded by rubbish. "Technically, my lord, an omniscope can see anywhere." said Arch chancellor Ridcully, who was technically the head of All Known Wizardry.*(*That is, all those wizards who knew Archchancellor Ridcully, and were prepared to be led.) "Really? Remarkable."
"Anywhere and any time." Ridcully went on, apparently not impressed himself. "How extremely useful."
"Yes, everyone says that," said Ridcully, kicking the floor morosely. "The trouble is, because the blasted thing can see everywhere, it's practically impossible to get it to see anywhere. At least, anywhere worth seeing. And you'd be amazed at how many places there are in the universe. And times, too."
"Twenty past one, for example." said the Patrician. "Among others, indeed. Would you care to have a look, my lord?" Lord Vetinari advanced cautiously and peered into the big round glass. He frowned. "All I can see is what's on the other side of it," he said. "All, that's because it's set to here and now, sir." said a young wizard who was still adjusting the device. "Oh, I see? said die Patrician. "We have these at the palace, in fact. We call them win-dows? "Well, if I do this? said the wizard, and did something to the rim of the glass, "it looks the other way." Lord Vetinari looked into his own face. "And these we call mir-rors? he said, as if explaining to a child. "I think not, sir." said the wizard. "It takes a moment to realise what you're seeing. It helps if you hold up your hand - -" Lord Vetinari gave him a severe look, but essayed a little wave. "Oh. How curious. What is your name, young man?"
"Ponder Stibbons. sir. The new Head of Inadvisably Applied Magic, sir. You see, sir. the trick isn't to build an omniscope because, after all, that's just a development of the old-fashioned crystal ball. It's to get it to see what you want. It's like tuning a string, and if-"
"Sorry, what applied magic?" said the Patrician. "Inadvisably, sir." said Ponder smoothly, as if hoping that he could avoid the problem by driving straight through it. "Anyway ... I think we can get it to the right area, sir. The power drain is considerable: we may have to sacrifice another gerbil." The wizards began to gather around the device. "Can you see into the future?" said Lord Vetinari. "In theory yes, sir," said Ponder. "But that would be highly ... well, inadvisable, you see, because initial studies indicate that the fact of observation would collapse the waveform in phase space." Not a muscle moved on the Patrician's face. "Pardon me, I'm a little out of date on faculty staff." he said. Are you the one who has to take the dried frog pills?"