'And, er, what would be the purpose of it?' said the Patrician. 'I believe it could replace the horse,' said Leonard proudly. They looked at the stricken thing. 'One of the advantages of horses that people often point out,' said Vetinari, after some thought, 'is that they very seldom explode. Almost never, in my experience, apart from that unfortunate occurrence in the hot summer a few years ago.' With fastidious fingers he pulled something out of the mess. It was a pair of cubes, made out of some soft white fur and linked together by a piece of string. There were dots on them. 'Dice?' he said. Leonard smiled in an embarrassed fashion. 'Yes. I can't think why I thought they'd help it go better. It was just, well, an idea. You know how it is.' Lord Vetinari nodded. He knew how it was. Be knew how it was far more than Leonard of Quirm did, which was why there was one key to the door and he had it. Not that the man was a prisoner, except by dull, humdrum standards. He appeared rather grateful to be confined in this light, airy attic with as much wood, paper, sticks of charcoal and paint as he desired and no rent or food bills to pay. In any case, you couldn't really imprison someone like Leonard of Quirm. The most you could do was lock up his body. The gods alone knew where his mind went. And, although he had so much cleverness it leaked continually, he couldn't tell you which way the political wind was blowing even if you fitted him with sails. Leonard's incredible brain sizzled away alarmingly, an overloaded chip pan on the Stove of Life. It was impossible to know what he would think of next, because he was constantly reprogrammed by the whole universe. The sight of a waterfall or a soaring bird would send him spinning down some

new path of practical speculation that invariably ended in a heap of wire and springs and a cry of 'I think I know what I did wrong.' He'd been a member of most of the craft guilds in the city but had been thrown out for getting impossibly high marks in the exams or, in some cases, correcting the questions. It was said that he'd accidentally blown up the Alchemists' Guild using nothing more than a glass of water, a spoonful of acid, two lengths of wire and a pingpong ball. Any sensible ruler would have killed off Leonard, and Lord Vetinari was extremely sensible and often wondered why he had not done so. He'd decided that it was because, imprisoned in the priceless, enquiring amber of Leonard's massive mind, underneath A that bright investigative genius was a kind of wilful innocence that might in lesser men be called stupidity. It was the seat and soul of that force which, down the millennia, had caused mankind to stick its fingers in the electric fight socket of the Universe and play with the switch to see what happened – and then be very surprised when it did. It was, in short, something useful. And if the Patrician was anything, he was the political equivalent of the old lady who saves bits of string because you never know when they might come in handy. After all, you couldn't plan for every eventuality, because that would involve knowing what was going to happen, and if you knew what was going to happen, you could probably see to it that it didn't, or at least happened to someone else. So the Patrician never planned. Plans often got in the way. And, finally, he kept Leonard around because the man was easy to talk to. He never understood what Lord Vetinari was talking about, he had a world view about as complex as that of a concussed duckling and, above all, never really paid attention. This made him an excellent confidant. After all, when you seek advice from someone it's certainly not because you want them to give it. You just want them to be there while you talk to yourself. 'I've just made some tea.' said Leonard. 'Will you join me?' He followed the Patrician's gaze to a brown stain all up one wall, which ended in a star of molten metal in the plaster. 'I'm afraid the automatical tea engine went wrong,' he said. 'I shall have to make it by hand.'

'So kind,' said Lord Vetinari. He sat down amidst the easels and, while Leonard busied himself at the fireplace, leafed through the latest sketches. Leonard sketched as automatically as other people scratched; genius – a certain kind of genius – fell off him like dandruff. There was a picture of a man drawing, the lines catching the figure so accurately it appeared to stand out of the paper. And around it, because Leonard never wasted white space, were other sketches, scattered aimlessly. A thumb. A bowl of flowers. A device, apparently, for sharpening pencils by water power...

Vetinari found what he was looking for in the bottom lefthand corner, sandwiched between a sketch for a new type of screw and a tool for opening oysters. It, or something very much like it, was always there somewhere. One of the things that made Leonard such a rare prize, and kept him under such secure lock and key, was that he really didn't see any difference between the thumb and the roses and the pencil–sharpener and this. 'Ah, the self–portrait,' said Leonard, returning with two cups. 'Yes, indeed,' said Vetinari. 'But my eye was drawn to this little sketch here. The war machine...'

'Oh, that? A mere nothing. Have you ever noticed the way in which the dew on roses–'

'This bit here... what is it for?' said Vetinari, pointing persistently. 'Oh, that? That's just the throwing arm for the balls of molten sulphur,' said Leonard, picking up a plate of small cakes. 'I calculate that one should get a range of almost half a mile, if one detaches the endless belt from the driving wheels and uses the oxen to wind the windlass.'

'Really?' said Vetinari, taking in the carefully numbered parts. 'And it could be built?'

'What? Oh, yes. Macaroon? In theory.'

'In theory?'

'No–one would ever actually do it. Raining unquenchable fire down upon fellow humans? Hah!' Leonard sprayed macaroon crumbs. 'You'd never find an artisan to build it, or a soldier who would pull the lever... That's part 3(b) on the plan, just here, look. ..'

'Ah, yes,' said Vetinari. 'Anyway,' he added, 'I imagine these huge power arms here couldn't possibly be operated without them breaking . . '

'Seasoned ash and yew, laminated and held together by special steel bolts,' said Leonard promptly. 'I made a few calculations, just there below the sketch of light on a raindrop. As an intellectual exercise, obviously.' Vetinari ran his eye along several lines of Leonard's spidery mirror–writing. 'Oh, yes,' he said glumly. He put the paper aside. 'Have I told you that the Klatchian situation is intensely political? Prince Cadram is trying to do a great deal very fast. He needs to consolidate his position. He is depending on support that is somewhat volatile. There are many plotting against. him, I understand.'

'Really? Well, this is the sort of thing people do,' said Leonard. 'Incidentally, I've recently been examining cobwebs and, I know this will interest you, their strength in relation to their weight is much greater even than our best steel wire. Isn't that fascinating?'

'What kind of weapon do you intend to make out of them?' said the Patrician. 'Sorry?'

'Oh, nothing. I was just thinking aloud.'

'And you haven't touched your tea,' said Leonard.

Vetinari looked around the room. It was full of... things. Tubes and odd paper kites and things that looked like the skeletons of ancient beasts. One of Leonard's saving graces, in a very real sense from Vetinari's point of view, was his strange attention span. It wasn't that he soon got bored with things. He didn't seem to get bored with anything. But since he was interested in everything in the universe all the time the end result tended to be that an experimental device for disembowelling people at a distance then became a string–weaving machine and ended up as an instrument for ascertaining the specific gravity of cheese. He was as easily distracted as a kitten. All that business with the flying machine, for example. Giant bat wings hung from the ceiling even now. The Patrician had been more than happy to let him waste his time on that idea, because it was obvious to anyone that no human being would ever be able to flap the wings hard enough. He needn't have worried. Leonard was his own distraction. He had ended up spending ages designing a special tray so that people could eat their meals in the air. A truly innocent man. And yet always, always, some little part of him would sketch these wretchedly beguiling engines, with their clouds of smoke and carefully numbered engineering diagrams... 'What's this?' Vetinari said, pointing to yet another doodle. It showed a man holding a large metal sphere. 'That? Oh, something of a toy, really. Makes use of the strange properties of some otherwise quite useless metals. They don't like being squeezed. So they go bang. With extreme alacrity.'

'Another weapon...'

'Certainly not, my lord! It would be no possible use as a weapon! I did think it might have a place in the mining industries, though.'

'Really...'

'For when they need to move mountains out of the way.'

'Tell me,' Vetinari said, putting this paper aside as well, 'you don't have any relatives in Klatch, do you?'

'I don't believe so. My family lived in Quirm for generations.'

'Oh. Good. But... very clever people in Klatch, are they?'

'Oh, in many disciplines they practically wrote the scroll. Fine metalwork, for example.'

'Metalwork.. .' The Patrician sighed. 'And Alchemy, of course. Affir Al–chema's Principia Explosia has been the seminal work for more than a hundred years.'

'Alchemy,' said the Patrician, glumly. 'Sulphur and so forth...'

'Yes, indeed.'

'But the way you put it, these major achievements were some considerable time ago...' Lord Vetinari sounded like a man straining to see a light at the end of the tunnel.

'Certainly! I would be astonished if they haven't made considerable progress!' said Leonard of Quirm happily. 'Ah?' The Patrician sank a little in his chair. It had turned out that the end of the tunnel was on fire. 'A splendid people with much to recommend them,' said Leonard. 'I always thought it was the presence of the desert. It leads to an urgency of thought. It makes you aware of the briefness of fife.' The Patrician glanced at another page. Between a sketch of a bird's wing and a careful drawing of a ball–joint was a little doodle of something with spiked wheels and spinning blades. And then there was the device for moving mountains aside... 'The desert is not required,' he said. He sighed again and pushed the pages aside. 'Have you heard about the lost continent of Leshp?' he said. 'Oh, yes. I did some sketches there a few years ago,' said Leonard. 'Some interesting aspects, I recall. More tea? I fear you've let that one get cold. Was there anything you particularly wanted?' The Patrician pinched the bridge of his nose. 'I'm not sure. There is a small problem developing. I thought perhaps you could help. Unfortunately,' the Patrician glanced at the sketches again, 'I suspect that you can.' He stood up, straightened his robe and forced a smile. 'You have everything you require?'

'Some more wire would be nice,' said Leonard. 'And I have run out of Burnt Umber.'

'I shall have some sent along directly,' said Vetinari. 'And now, if you will excuse me–' He let himself out. Leonard nodded happily as he cleared away the teacups. The infernal combustion engine was carried to the heap of scrap metal beside the small forge, and he fetched a ladder and removed the piston from the ceiling. He'd just opened out his easel to start work on a new design when he was aware of a distant pattering. It sounded like someone running but also occasionally pausing to hop sideways on one leg. Then there was a pause, such as might be made by someone adjusting their clothing and getting their breath back. The door opened and the Patrician returned. He sat down and looked carefully at Leonard of Quirm. 'You did what?' he said. Vimes turned the clove over and over under the magnifying glass. 'I see tooth marks,' he said. 'Yes sir,' said Littlebottom, who represented in her entirety the watch's forensic department. 'Looks like someone was chewing it like a toothpick.' Vimes sat back. 'I would say,' he said, 'that this was last touched by a swarthy man of about my height. He had several gold teeth. And a beard.