'Don't you mean will be,' said Sweeper. 'No! You told me it helps if I think of things happening one after another! Well, yesterday, my yesterday, I was Commander of the Watch and I bloody well still am the Commander of the Watch. I don't care what anyone else thinks. They are not in possession of all the facts!'

'Hold on to that thought,' said Sweeper, standing up. 'All right, commander. You want some facts. Let's take a walk in the garden, shall we?'

'Can you get me home?'

'Not yet. It's my professional opinion that you're here for a reason.'

'A reason? I fell through the bloody dome!'

'That helped, yes. Calm down, Mister Vimes. It's all been a great strain, I can see.' Sweeper led the way out of the hall. There was a big office outside, a hubbub of quiet but purposeful activity. Here and there, among the worn and scratched desks, there were more cylinders like the ones Vimes had seen in the other chamber. Some of them were turning slowly. 'Very busy, our Ankh-Morpork section,' said Sweeper. 'We had to buy the shops on either side.' He picked up a scroll from a basket by one desk, glanced at the contents, and tossed it back with a sigh. 'And everyone's overworked,' he added. 'We're here at all hours. And when we say “all hours”, we know what we're talking about.'

'But what is it you do?' said Vimes. 'We see that things happen.'

'Don't things happen anyway?'

'Depends what things you want. We're the Monks of History, Mister Vimes. We see that it happens.'

'I've never heard of you, and I know this city like the back of my hand,' said Vimes. 'Right. And how often do you really look at the back of your hand, Mister Vimes? We're in Clay Lane, to stop you wondering.'

'What? Those loony monks in the funny foreign building between the pawnbrokers and the shonky shop? The ones who go dancing round the street banging drums and shouting?'

'Well done. Mister Vimes. It's funny how secretly you can move when you're a loony monk dancing through the streets banging a drum.'

'When I was a kid most of my clothes came from the shonky shop in Clay Lane,' said Vimes. 'Everyone we knew got their clothes from the shonky shop. Used to be run by a foreign guy with a funny name.'

'Brother Soon Shine Sun,' said Sweeper. 'Not a hugely enlightened operative, but a genius when it comes to pricing fourth-hand schmutter.'

'Shirts so worn you could see daylight through 'em and trousers as shiny as glass,' said Vimes. 'And by the end of the week half the stuff was in the pawn shop.'

'That's right,' said Sweeper. 'You'd pawn your clothes in the pawn shop, but you'd never buy clothes from the pawn shop, 'cos there were Standards, right?' Vimes nodded. When you got right down to the bottom of the ladder the rungs were very close together and, oh my, weren't the women careful about them. In their own way, they were as haughty as any duchess. You might not have much, but you could have Standards. Clothes might be cheap and old but at least they could be scrubbed. There might be nothing behind the front door worth stealing but at least the doorstep could be clean enough to eat your dinner off, if you could've afforded dinner. And no one ever bought their clothes from the pawn shop. You'd hit bottom when you did that. No, you bought them from Mr Sun at the shonky shop, and you never asked where he got them from. 'I went off to my first proper job in a suit from the shonky shop,' he said. 'Seems like centuries ago now.'

'No,' said Sweeper. 'It was only last week.' Silence ballooned. The only sound was the purr of the cylinders dotted around the room. Then Sweeper added: 'It must have occurred to you.'

'Why? I've spent most of the time here being beaten up or unconscious or trying to get home! You mean I'm out there somewhere?'

'Oh, yes. In fact last night you saved the day for your squad by aiming a crossbow at a dangerous miscreant who was attacking your sergeant.'

The silence ballooned larger this time. It seemed to fill the universe. Eventually, Vimes said: 'No. That's not right. That never happened. I would have remembered that. And I can remember a lot about my first weeks in the job.'

'Interesting, isn't it?' said Sweeper. 'But is it not written: “There's a lot goes on we don't get told”? Mister Vimes, you need a short spell in the Garden of Inner City Tranquillity.' It was indeed a garden, like a lot of other gardens you got in areas such as Clay Lane. The grey soil was nothing more than old brick dust, elderly cat mess and generalized, semi-rotted dross. At the far end was a three- hole privy. It was built handily by the gate to the back lane so the night-soil men didn't have far to go, but this one had a small stone cylinder turning gently beside it and the gate was barred shut. The garden didn't get much proper light. Gardens like this never did. You got second-hand light once the richer folk in the taller buildings had finished with it. Some people kept pigeons or rabbits or pigs on their plots, or planted against all experience a few vegetables. But it'd take magic beans to reach the real sunlight in gardens like this. Nevertheless, someone had made an effort. Most of the spare ground had been covered with gravel of different sizes, and this had been carefully raked into swirls and curves. Here and there, apparently with great thought, some individual larger stones had been positioned. Vimes stared at the garden of rocks, desperate for anything to occupy his attention. He could see what the designer had in mind, he thought, but the effect had been spoiled. This was the big city, after all. Garbage got everywhere. The main disposal method was throwing it over a wall. Sooner or later someone would sell it on or, possibly, eat it. A young monk was carefully raking the gravel. He gave a respectful bow as Sweeper approached. The old man sat down on a stone bench. 'Push off and get us two cups of tea, lad, will you?' he said. 'One green with yak butter, and Mister Vimes will have it boiled orange in a builder's boot with two sugars and yesterday's milk, right?'

'That's how I like it,' said Vimes weakly, sitting down. Sweeper took a deep, long breath. 'And I like building gardens,' he said. 'Life should be a garden.' Vimes stared blankly at what was in front of them. 'Okay,' he said. 'The gravel and rocks, yes, I can see that. Shame about all the rubbish. It always turns up, doesn't it . . .'

'Yes,' said Lu-Tze. 'It's part of the pattern.'

'What? The old cigarette packet?'

'Certainly. That invokes the element of air,' said Sweeper. 'And the cat doings?'

'To remind us that disharmony, like a cat, gets everywhere.'

'The cabbage stalks? The used sonky?'* * Named after Wallace Sonky, a man without whose experiments with thin rubber the pressure on housing in Ankh-Morpork would have been a good deal more pressing. 'At our peril we forget the role of the organic in the total harmony. What arrives seemingly by chance in the pattern is part of a higher organization that we can only dimly comprehend. This is a very important fact, and has a bearing on your case.'

'And the beer bottle?' For the first time since Vimes had met him, the monk frowned. 'Y'know, some bugger always tosses one over the wall on his way back from the pub on Friday nights. If it wasn't forbidden to do that kind of thing, he'd feel the flat of my hand and no mistake.'

'It's not part of the higher organization?'

'Possibly. Who cares? That sort of thing gets on my thungas, it really does,' said Sweeper. He sat back with his hands on his knees. Serenity flowed once more. 'Well now, Mister Vimes . . . you know the universe is made up of very small items?'

'Huh?'

'We've got to work up to things gradually, Mister Vimes. You're a bright man. I can't keep telling you everything is done by magic.'

'Am I really here too? In the city? I mean, a younger me?'

'Of course. Why not? Where was I? Oh, yes. Made up of very small items, and-'

'This is not a good time to be in the Watch. I remember! There's the curfew. And that was only the start!'

'Small items, Mister Vimes,' said Sweeper sharply. 'You need to know this.'

'Oh, all right. How small?'

'Very, very small. So tiny that they have some very strange ways indeed.' Vimes sighed. 'And I ask you: what ways are these, yeah?'

'I'm glad you asked that question. For one thing, they can be in many places at once. Try to think, Mister Vimes.'

Vimes tried to concentrate on what was probably the discarded fish-and- chip wrapper of Infinity. Oddly enough, with so many horrible thoughts crowding his head, it was almost a relief to put them on one side in order to consider this. The brain did things like that. He remembered once when he'd been stabbed and would've bled to death if Sergeant Angua hadn't caught up with him, and how, as he lay there, he'd found himself taking a very intense interest in the pattern of the carpet. The senses say: we've only got a few minutes, let's record everything, in every detail. . . 'That can't be right,' he said. 'If this seat is made up of lots of tiny things that can be in lots of places at once, why is it standing still?'

'Give the man a small cigar!' said Sweeper jubilantly. That's the big problem, Mister Vimes. And the answer, our Abbot tells us, is that it is in lots of places at once. Ah, here's the tea. And in order for it to be in lots of places at once, the multiverse is made up of a vast number of alternative universes. An oodleplex of oodleplexes. That's like the biggest number anyone can think of, ever. Just so's it can accommodate all the quantum. Am I going too fast for you?'

'Oh, that,' said Vimes. 'I know about that. Like, you make a decision in this universe and you made a different decision in another one. I heard the wizards talking about that at a posh reception once. They were . . . arguing about the Glorious Twenty-fifth of May.'

'And what were they saying?'

'Oh, all the old stuff. . . that it would have turned out different if the rebels had properly guarded the gates and the bridges, that you can't break a siege by a frontal attack. But they were saying that, in a way, everything happens somewhere 'And you believed them?'

'It sounds like complete thungas. But sometimes you can't help wondering: what would have happened if I'd done something different-'

'Like when you killed your wife?' Sweeper was impressed at Vimes's lack of reaction. 'This is a test, right?'

'You're a quick study, Mister Vimes.'

'But in some other universe, believe me, I hauled off and punched you one.' Again, Sweeper smiled the annoying little smile that suggested he didn't believe him. 'You haven't killed your wife,' he said. 'Anywhere. There is nowhere, however huge the multiverse is, where Sam Vimes as he is now has murdered Lady Sybil. But the theory is quite clear. It says that if anything could happen without breaking any physical laws, it must happen. But it hasn't. And yet the “many universes” theory works. Without it, no one would ever be able to make a decision at all.'

'So?'

'So what people do matters!' said Sweeper. 'People invent other laws. What they do is important. The Abbot's very excited about this. He nearly swallowed his rusk. It means the multiverse isn't infinite and people's choices are far more vital than they think. They can, by what they do, change the universe.' Sweeper gave Vimes a long look. 'Mister Vimes, you're thinking: I'm back in time, and damn me, I'm probably going to end up being the sergeant that teaches me all I know, right?'

'I've been wondering. The Watch would offer any gutter trash a job in those days, because of the curfew and all the spying. But look, I remember Keel and, yes, he did have a scar and an eye-patch but I'm sure as hell that he wasn't me.'

'Right. The universe doesn't work like that. You were indeed taken under the wing of one John Keel, a watchman from Pseudopolis who came to Ankh- Morpork because the pay was better. He was a real person. He was not you. But do you remember if he ever mentioned to you that he was attacked by two men not long after he got off the coach?'