Discworld is a world and a mirror of worlds.

This is not a book about Australia. No, it's about somewhere entirley different which just happens to be, here and there, a bit... Australian.

Still... no worries, right?

Against the stars a turtle passes, carrying four elephants on its shell.

Both turtle and elephants are bigger than people might expect, but out between the stars the difference between huge and tiny is, comparatively speaking, very small.

But this turtle and these elephants are, by turtle and elephant standards, big. They carry the Discworld, with its vast lands, cloudscapes, and oceans.

People don't live on the Disc any more than, in less hand-crafted parts of the multiverse, they live on balls. Oh, planets may be the place where their body eats its tea, but they live elsewhere, in worlds of their own which orbit very handily around the centre of their heads.

When gods get together they tell the story of one particular planet whose inhabitants watched, with mild interest, huge continent-wrecking slabs of ice slap into another world which was, in astronomical terms, right next door – and then did nothing about it because that sort of thing only happens in Outer Space. An intelligent species would at least have found someone to complain to. Anyway, no one seriously believes in that story, because a race quite that stupid would never even have discovered slood.

People believe in all sorts of other things, though. For example, there are some people who have a legend that the whole universe is carried in a leather bag by an old man.

They're right, too.

Other people say: hold on, if he's carrying the entire universe in a sack, right, that means he's carrying himself and the sack inside the sack, because the universe contains everything. Including him. And the sack, of course. Which contains him and the sack already. As it were.

To which the reply is: well?

All tribal myths are true, for a given value of 'true'.

It is a general test of the omnipotence of a god that they can see the fall of a tiny bird. But only one god makes notes, and a few adjustments, so that next time it can fall faster and further.

We may find out why.

We might find out why mankind is here, although that is more complicated and begs the question 'Where else should we be?' It would be terrible to think that some impatient deity might part the clouds and say, 'Damn, are you lot still here? I thought you discovered slood ten thousand years ago! I've got ten trillion tons of ice arriving on Monday!'

We may even find out why the duck-billed platypus.

Snow, thick and wet, tumbled on to the lawns and roofs of Unseen University, the Discworld's premier college of magic.

It was sticky snow, which made the place look like some sort of expensive yet tasteless ornament, and it caked around the boots of McAbre, the Head Bledlow, as he trudged through the cold, wild night.

Two other bledlows stepped out of the lee of a buttress and fell in behind him on a solemn march towards the main gates.

It was an old custom, centuries old, and in the summer a few tourists would hang around to watch it, but the Ceremony of the Keys went on every night in every season. Mere ice, wind and snow had never stopped it. Bledlows in times gone past had clambered over tentacled monstrosities to do the Ceremony; they'd waded through floodwater, flailed with their bowler hats at errant pigeons, harpies and dragons, and ignored mere faculty members who'd thrown open their bedroom windows and screamed imprecations on the lines of 'Stop that damn racket, will you? What's the point!' They'd never stopped, or even thought of stopping. You couldn't stop Tradition. You could only add to it.

The three men reached the shadows by the main gate, almost blotted out in the whirling snow. The bledlow on duty was waiting for them.

'Halt! Who Goes There?' he shouted.

McAbre saluted. The Archchancellor's Keys!'

'Pass, The Archchancellor's Keys!'

The Head Bledlow took a step forward, extended both arms in front of him with his palms bent back towards him, and patted his chest at the place where some bledlow long buried had once had two breast pockets. Pat, pat. Then he extended his arms by his sides and stiffly patted the sides of his jacket. Pat, pat.

'Damn! Could Have Sworn I Had Them A Moment Ago!' he bellowed, enunciating each word with a sort of bulldog carefulness.

The gatekeeper saluted. McAbre saluted.

'Have You Looked In All Your Pockets?'

McAbre saluted. The gatekeeper saluted. A small pyramid of snow was building up on his bowler hat.

'I Think I Must Have Left Them On The Dresser. It's Always The Same, Isn't It?'

'You Should Remember Where You Put Them Down.!'

'Hang On, Perhaps They're In My Other Jacket!'

The young bledlow who was this week's Keeper of the Other Jacket stepped forward. Each man saluted the other two. The youngest cleared his throat and managed to say:

'No, I Looked In... There This... Morning!'

McAbre gave him a slight nod to acknowledge a difficult job done well, and patted his pockets again.

'Hold On, Stone The Crows, They Were In This Pocket After All! What A Muggins I Am!'

'Don't Worry, I Do The Same Myself!'

'Is My Face Red! Forget My Own Head Next!'

Somewhere in the darkness a window creaked up.

'Er, excuse me, gentlemen—'

'Here's The Keys, Then!' said McAbre, raising his voice.

'Much Obliged!'

'I wonder if you could—' the querulous voice went on, apologizing for even thinking of complaining.

'All Safe And Secure!' shouted the gatekeeper, handing the keys back.

'—perhaps keep it down a little—'

'Gods Bless All Present!' screamed McAbre, veins standing out on his thick crimson neck.

'Careful Where You Put Them This Time. Ha! Ha! Ha!'

'Ho! Ho! Ho!' yelled McAbre, beside himself with fury. He saluted stiffly, went About Turn with an unnecessarily large amount of foot stamping and, the ancient exchange completed, marched back to the bledlows' lodge muttering under his breath.

The window of the University's little sanatorium shut again.

That man really makes me want to swear,' said the Bursar. He fumbled in his pocket and produced his little green box of dried frog pills, spilling a few as he fumbled with the lid. I've sent him no end of memos. He says it's traditional but, I don't know, he's so... boisterous about it...' He blew his nose. 'How's he doing?'

'Not good,' said the Dean.

The Librarian was very, very ill.

Snow plastered itself against the closed window.

There was a heap of blankets in front of the roaring fire. Occasionally it shuddered a bit. The wizards watched it with concern.

The Lecturer in Recent Runes was feverishly turning over the pages of a book.

'I mean, how do we know if it's old age or not?' he said. 'What's old age for an orang-utan? And he's a wizard. And he spends all his time in the Library. All that magic radiation the whole time. Somehow the flu is attacking his morphic field, but it could be caused by anything.'

The Librarian sneezed.

And changed shape.

The wizards looked sadly at what appeared very much like a comfortable armchair which someone had, for some reason, upholstered in red fur.

'What can we do for him?' said Ponder Stibbons, the Faculty's youngest member.

'He might feel happier with some cushions,' said Ridcully.

'Slightly bad taste, Archchancellor, I feel.'