The Globe

What else do they need?'

'But it must get cold in the winter, surely?'

'So? It gets warmer in the spring! It's just like the moon and the stars! Things happen!'

'And they've been like this for hundreds of thousands of years,' said Ponder.

There was some more silence.

'Remember those stupid big lizards?' said the Dean. 'They lasted for more than a hundred million years, I remember. I suppose they were quite successful, in their way.'

'Successful?' said Ridcully.

'I mean they lasted a long time.'

'Really? And did they build a single university?'

'Well, no—'

'Did they draw a single picture? Invent writing? Offer even small classes of elementary tuition?'

'Not that I know—'

'And they all got killed off by a yet another big rock,' said Ridcully. 'They really did not know what hit them. Bein' around for millions of years is not an achievement. Even lumps of stone can manage that.'

The circle of wizards was sunk in gloom.

'And Dee's people were doin' quite well,' muttered Ridcully. 'Terrible beer, of course.'

'I suppose ...' Rincewind began.

'Yes?' said the Archchancellor.

'Well ... how about if we went back and stopped us from stopping the elves? And least we'd be back among people more interesting than cows.'

'Could we do that?' said Ridcully to Ponder.

'I suppose so,' said Ponder. 'Technically, if we stop ourselves, then nothing will change, I assume. All this won't have happened ... I think. That is to say, it will have happened, because we'll remember it, but then it won't have happened.'

'Fair enough,' said Ridcully. Wizards do not have a lot of patience with temporal paradoxes.

'Can we stop ourselves?' said the Dean. 'I mean, how do we do it?'

'We'll just explain the situation to us,' said Ridcully. 'We're reasonable men.'

'Hah!' said Ponder, and then looked up. 'Oh, sorry, Archchancellor. I must have been thinking about something else. Do go on.'

'Ahem. If I was just about to fight elves, and someone who looked very much like me came up and told me not to, I'd assume it was an elvish trick,' said the Lecturer in Recent Runes. 'They can make you think they look like someone else, you know.'

'I'd know me if I saw me!' said the Dean.

'Look, it's easy,' said Rincewind. 'Trust me. Just tell yourself something about yourself that no one else could possibly know.'

A worried look crossed the Dean's face.

'Would that be wise?' he said. Like many people, wizards often have secrets they don't want themselves to know.

Ridcully stood up. 'We know it'll work,' he said, 'because it's already happened to us. Think about it. We must succeed in the end, because we know a species like this gets off the planet.'

'Yes,' said Ponder, slowly, 'and, then again, no.'

'What the hell does that mean?' Ridcully demanded.

'Well ... we've been to a future where it happens, certainly,' said Ponder, twiddling his pencil nervously. 'But there are other futures. The multiplex nature of the universe that allows it to absorb and cushion the effects of apparent paradoxes also means that nothing is certain, even if you know it is.' He tried to avoid Ridcully's stare. 'We went to a future. At the moment, it exists only in our memories. Then, it was real. Now, it may never be. Look, Rincewind was telling me about some play writer he's found, born around about Dee's time but not in this branch of the universe. Yet we know he has an existence, because L-space contains all possible books in all possible histories. Do you see what I mean? Nothing is certain.'

After a while, the Chair of Indefinite Studies said, 'You know, I think I prefer the kind of universal law that says the third son of a king always gets the princess. They make sense.'

'The universe is so big, sir, that it obeys all possible laws,' said Ponder. 'For a given value of

"teapot".'

'Look, if we go back in time and talk to ourselves, why don't we remember it?' said the Lecturer in Recent Runes.

Ponder sighed. 'Because although it has already happened to us, it hasn't yet happened to us.'

'I, er, tried something like that,' said Rincewind. 'While you were having your mussel soup just now I got Hex to send me back in time to warn myself to hold my breath when we landed in the river. It worked.'

'Did you hold your breath?' 'Yes, because I've warned myself.'

'So ... was there any time anywhere where you didn't hold your breath, thus giving yourself a mouthful of river water and causing you to go back to make sure you did?'

'Probably there was, I think, but there isn't now.' 'Oh, I see,' said the Lecturer in Recent Runes.

'You know, it's a good job we're wizards, otherwise this time travel business could really be confusing ...'

'At least we know that Hex can still make contact with us,' said Ponder. 'I'll ask him to move us back again.' The Librarian watched them go. A moment later, the rest of everywhere went with them.

FOURTEEN

The Ugs have no real stories, hence no sense of their place in time. They have no conception of the future, and therefore no wish to change it.

We know that there are other futures ... As Ponder Stibbons remarks, we live in a multiplex universe. We look at the past and we see times and places where things could have been different, and we wonder whether we could have ended up in a different present. By analogy, we look at the present and imagine many different futures. And we wonder which of them will happen, and what we can do now to affect the choice.

We could be wrong. Maybe the fatalist view, 'it is written', is right. Maybe we are all automata, working out the deterministic future of a clockwork universe. Or maybe the Quantum philosophers are right, and all possible futures (and pasts) coexist. Or maybe everything that exists is just one point in a multiplex phase space of universes, a single card dealt from Fate's deck.

How did we acquire this sense of ourselves as beings who exist in time? Who remember their past, and use it to try (usually unsuccessfully) to control their future?

It all goes back a long, long way.

Watch a proto-human watching a zebra watching a lioness. The three mammalian brains are doing very different things. The herbivore brain has seen the lioness, is barely conscious (we guess, watch some horses in a field) of the whole 360 degrees of his environment, and has marked some things, like that tuft of grass over there, that female over there who could just be in heat, that male who's giving her the right signals, the three bushes that could have a surprise behind them .. the lioness moves, she suddenly gets priority, but not totally because there are other considerations. Another lioness could well be behind those bushes, and I'd better move up on that nice grass before Nigella does ... Looking at that grass makes me think of the taste of that long grass ... THE LIONESS IS MOVING.

The lioness is thinking: that's a nice zebra stallion, won't go for him he's too strong (memory of a previous eye injury from a zebra kick) but if I get him running, Dora behind those bushes can probably jump on the young female over there who is trying to attract the male, then I can run after it with her ...

There is probably no more of a plan than that in the zebra's brain but it does foresee a little bit of the future and plug memories into present planning. If I stand up now ...

The human is looking at the lioness and the zebra. Even if it's a Homo erectus, we bet it had stories in its head: that lioness will run out, the zebra will startle, the other lioness will go for ...