About five miles north of Coventry, just off the A21, there is a house. It is, in all respects, a perfectly normal house. It has windows, doors, an interior divided for convenience into a number of subsets of space designated for the particular purposes of eating, sleeping and storing old issues of the Sunday Times Magazine. 
This house, in short, is indistinguishable from any one of the several hundred thousand dwellings constructed by the ape-descended bipedal inhabitants of the particular land mass on which it is located. No one is going to admire its unique architecture, write a feature about it in Architectural Digest, or turn up with a camera crew to film an especially irritating programme for Channel Four about how to make money out of renovating property. It is, in short, an utterly unremarkable house.
The only person to whom the house is not unremarkable is Arthur Dent, and that is only because he lives in it.
And this is the curious thing, because Arthur Dent, like his house, looks indistinguishable from any of the several hundred thousand or so ape-descended bipedal inhabitants of the land mass on which the house happens to be located. Very much unlike his house, however, he is very different indeed. One of these differences -- although by no means the primary one -- is the sheer number and variety of places Arthur has lived in his (typically for an ape-descended biped) short and (atypically) eventful life.
For those keeping track of where Arthur Dent had lived so far (and it would be fair to say that Arthur himself long ago stopped trying), a brief tally would go something like this:
- Number 42, Chance Gardens, Wokingham, Surrey
- Berth 5, the Starship Heart of Gold
- A small hut on the planet Lamuella
- Two memorable, but still inadequately explained, weeks in the boudoir of Eccentrica Gallumbits, the triple-breasted whore of Eroticon Six
Further to this list, it is worth noting two things:
- Every place where Arthur Dent has lived, except his current residence, has been blown up, imploded, rendered uninhabitable by radiation, seared by death rays or, on one occasion, flooded by mucus from a giant Hiryaniam MegaSlug; and
- Arthur's local branch of Nat West has never, not once, acknowledged even one of the change of address letters he has been sending them since 1983.
Arthur has lived in his current home for five years.
He does not intend ever moving again.
Arthur got out of bed, put on his slippers, pulled open the curtains of his bedroom and checked the front of the house for bulldozers. He did this every morning, without fail. This morning, as every morning, he felt a surge of relief when there weren't any.
He went downstairs, knocking over a pile of old issues of the Sunday Times Magazine which he'd left on the bottom step and meant to get around to throwing out some time, and went to the kitchen to make himself breakfast. In the kitchen, he put on the kettle to make tea, and turned on the radio. It was tuned to Radio Four, and Arthur let the Today programme meander aimlessly through his consciousness as he popped tea bags into the teapot, poured Kelloggs Just Right into a bowl and sniffed the milk cautiously. It was a Thursday, there was tea brewing, and on the airwaves John Humphrys was being gratuitously hostile to the Minister for Transport. All was, if not right with the world, at least normal. In spite of feeling an occasional twinge of something that might have been dissatisfaction, Arthur had come to regard this state of affairs as a tolerable second-best.
"Morning," said Ford Prefect, who was sitting at Arthur's kitchen table.
Arthur yelled in surprise and dropped his bowl of cereal on the floor.
"I made coffee, I hope you don't mind," Ford said, indicating the mug he was holding in his left hand. It was a 'humorous' mug which one of the research assistants at the local radio station where Arthur worked had given him the previous Christmas. It bore a picture of a knife dripping gore and the motto Serial killers do it 'til they're stopped. Arthur had tried many times to accidentally drop it.
"You appear to have dropped your cereal," Ford said.
"So I have," Arthur said tightly. He was regaining some of his composure now and, he thought privately, he wasn't doing too badly. Although for someone who'd had his composure disturbed, on so many occasions and in so many ways, he had hoped to be a little better at it by now. "Ford, what are you doing here?"
Ford smiled cheerfully. "Well, I just thought I'd drop in and see you. Chew the fat, rake the old coals, other apposite metaphors."
"How did you get here?" Arthur held up a hand. "No, don't tell me. You hitched a lift."
Ford made a small noise that sounded to Arthur like, "Pffft." He said, "Space travel is so last century, now. I came by Universe Shifter."
Arthur had the distinct feeling he was going to regret asking the obvious question, so he didn't. Instead he got a cloth from next to the sink and went about cleaning up the mess of soggy Just Right which was pooling on the kitchen lino. When he'd finished and looked in Ford's direction again, Ford was still sitting at Arthur's kitchen table, drinking Arthur's coffee and smiling with a kind of vague hopefulness in Arthur's direction.
"If I concentrate hard enough on ignoring you," Arthur asked as he mopped determinedly, "is there even the slightest chance you'll vanish again?"
"Sorry," Ford said, sounding not in the least bit apologetic. "I'm not an Ebullian Weaver Bird, you know."
"An Ebullian --?" Arthur clamped his mouth shut, but it was too late. Ford snared the half-formed question and attacked it with zest.
"The Ebullian Weaver Bird. It's extinct. There was an accident with a time machine and a Super-Evolver."
The clock on the kitchen wall said 8.05. Usually, by now, Arthur had eaten his Kelloggs All Bran, drunk his tea, and was heading back up the stairs to get dressed and check for bulldozers again. For a brief, crazed moment, he considered doing that anyway.
He didn't. Instead he sat down at the kitchen table, opposite Ford. "You're going to tell me what a Super-Evolver is whether I ask you about it or not, aren't you?"
Ford started to talk, his voice rising with enthusiasm. "The Galactic Society for the Prevention of Unnecessary Extinctions invented it. They pick an animal that's in danger of dying out, then go back in time and use the Super-Evolver to make sure it develops in ways that give it the qualities it needs to survive. Sometimes they get a little overenthusiastic, though -- that's how we ended up with the Rabid Attack Dodo of Hrrrgrrrrfurr Five. You wouldn't want to meet one of those unless you had several fully-charged UltraKil Blast Rifles to hand."
"I should think not," Arthur said. "And the Ebullian Weaver Bird?"
Ford shrugged. "The Super-Evolver was supposed to enhance the Ebullian Weaver Bird's natural camouflage so it could hide from predators -- mostly Ebullian advertising executives with weekend hunting passes -- more effectively. Unfortunately, it enhanced them to the point where the Weaver Bird couldn't get noticed, even by other Weaver Birds. They died out because they couldn't find each other to mate. It's rather sad, really. Especially," Ford added, in a tone that suggested he personally didn't give two hoots whether there were two Ebullian Weaver Birds or two gigillion, "because the Super-Evolver was so efficient, the Weaver Bird actually became extinct before it evolved."
"That's not possible," Arthur said.
"Try telling that to an Ebullian Weaver Bird," Ford said. Triumphantly, he concluded, "But you wouldn't be able to find one to tell it, because they're extinct."
Arthur blinked, suddenly understanding what it feels like to be a hydrogen atom shot out of a particle accelerator. He often felt this way around Ford: every conversation would begin with Arthur determined not to get sucked into another surreal chain of logic so fuzzy you could knit a rather fetching sweater from it, and yet somehow after only a few minutes he would find himself trying to make his brain perform the equivalent of five-dimensional yoga as he attempted to follow Ford's line of -- no, he corrected himself, Ford's multi-angled non-regular polygon of reasoning. He hadn't had a conversation like this in -- well, in fifteen years, he supposed.
The surprising part was how much he was suddenly enjoying himself.
"The Ebullian Weaver Bird is one of only five creatures to have become extinct before they ever existed in the first place," Ford said. He took another swig from Arthur's coffee mug, set it down and began to talk, gesturing animatedly as he did so. "The others are the Gargantuan Flog of Miniscon Seven, the Ruddy-Nosed Hobble Plodder of Debeneva, the --"
"Wait, wait, wait!" Arthur exclaimed. "Ford. Look. It is nice to see you. Perhaps later we can go and have a pint, catch up on news and perhaps, just for old times' sake, we'll round out the evening with a terrifying brush with death. But what I'd really like to know now is the answer to the question I believe I asked as soon as I saw you and to which I still don't have a satisfactory answer. What are you doing here?"
"I'm writing a book," Ford said. There was that smile again -- hopeful and, unusually for Ford, slightly uncertain.
Arthur frowned. "You're not working for the Guide any more?"
Ford's brow furrowed and his mouth hardened into a thin, harsh line. "The Guide's gone corporate." He brightened. "Besides, people don't want their facts battery-farmed and organised these days. They want to stumble on knowledge. They want to feel they've found things out for themselves. Hence, a miscellany." 
"A miscellany," Arthur repeated, rolling the sound out of his mouth experimentally. It felt more like a type of pasta than a word.
"Right," Ford said. "Lots and lots of interesting things, jumbled together in no order. An assortment of asinine information. A mass of minutiae."
"Thank you," Arthur interrupted him. "There's no need to alliterate me to death. And this -- this miscellany -- it would include such things as the only five creatures to become extinct before they evolved?"
Ford nodded so vigorously that for a moment Arthur thought his head would fall off. Granted, he'd never actually seen Ford's head fall off, but when a man was from Betelguese who was to say how solidly his head was attached to his shoulders? Or not?
Arthur's own head was starting to feel a little loose.
"So, there I was," Ford said, "thinking about how I was going to research this book -- I'm going to call it A Galactic Miscellany, snappy title, eh? -- and I thought, who'd be up for that? My old friend Arthur, that's who! And here I am!" he concluded, with an eagerness which was, in the face of Arthur's steadfast non-reaction, becoming more forced by the picosecond. 
After a moment, he tried again. "You and me! Just like old times! Getting thrown out of spaceships, finding the Question to the Ultimate Answer to life, the universe and everything, getting marooned in the distant past with only a bunch of telephone sanitisers for company..." He trailed off.
Arthur regarded him levelly.
"Er," Ford said.
"Ford," Arthur said, "you know where we are, don't you?"
"We're on the third planet out from an insignificant yellow star in the unfashionable end of the western spiral arm of the galaxy," Ford said. "And about ten minutes from the big Sainsbury's in Coventry."
Arthur nodded. "We're on Earth, Ford. I am on Earth. I am living on a planet which I know for a fact was blown up by the Vogons to make way for a totally unnecessary hyperspace by-pass, and which by rights should not be here at all. The only reason it is here is because of some mind-bendingly complex warping of the laws of dimensional probability that will make me gibber if I think too hard about it. So I don't think about it. Instead I get up every morning, I go to work, I pay my mortgage and I --" Here, Arthur leaned forward, across the table, so that he was eyeballing Ford: "This is the important part, so do listen carefully: I do not do anything out of the ordinary. At all. Ever." He paused. "Well, I did sign up for OnDigital, but I think everyone should be allowed the occasional minor lapse."
"So you're saying you don't want to come with me."
"I'd sooner push knitting needles up my nose and stand for election as leader of the Conservative Party."
Ford visibly wilted.
"I hoped," he said, and stopped.
He tried again. "I sort of thought that --"
At last, he said, "It wouldn't be the same without you."
Sitting at Arthur's kitchen table, one hand wrapped around Arthur's novelty serial killer mug, Ford looked suddenly older than Arthur remembered him. Which was odd, Arthur thought, because he was certain he remembered a drunken conversation in a bar on Gargalto Two during which Ford had insisted that Beteguesans lived for many hundreds of years longer than humans. Of course, Ford had drunk several pan-Galactic Gargle Blasters by that point in the evening, which meant that he had been insisting all kinds of things, including that the colour taupe was the root cause of all universal conflict and that the American daytime soap opera General Hospital was written by the CIA.  But something had given Arthur the idea he'd been telling the truth about his lifespan.
He'd known Ford now for years -- no, he corrected himself with a small shiver of shock, for decades. It had been more than twenty years since the party in Islington where he'd met the slightly dishevelled and more than slightly drunk man who'd claimed to be from Guildford and who couldn't understand why everyone kept asking him if that really was his name. In fact, given the amount of time travelling they'd done, it was perfectly possible that by now Arthur had been friends with Ford for longer than the Earth had existed. He'd seen the many moods of Ford: happy, drunk, angry, drunk, terrified, drunk, cynical, and drunk. Mostly, now he thought about it, drunk.
But he had never seen Ford looking lost, the way he did now. Ford didn't get lost. Whether they had been wading ecstatically through the Saskakillian Pleasure Swamps or fighting against the non-flow of the traffic in the Endless Commute on Joolude Nine, Ford had always known exactly what way to turn next, which direction to strike out in. Ford had written the book on galactic hitch-hiking. Literally.
Arthur looked around his calm, ordered kitchen and suddenly realised exactly what his calm, ordered suburban life had been lacking for the past fifteen years.
I'm going to regret this, he thought.
Then he thought, for perhaps the first time in his life: What the hell.
"Wait here," Arthur said. "I'm just going to pop upstairs and get my towel."
The Universe Shifter is a marvellous new way of traversing vast galactic distances without enduring all that tedious waiting around in spaceport lounges.
This is how it works:
The traveller picks a spot and stands very, very still. Then he, she, or it concentrates very, very hard on the place he, she or it wants to be. It is vitally important that the traveller has an extremely clear, focused and definite idea of the destination. People who are inclined to leave the house and then remember, half way down the drive, that they left the gas on should on no account use the Universe Shifter.
What happens next is really quite straightforward. The traveller stays still while the Universe Shifter moves the universe so that the traveller is exactly where he, she or it wants to be.
The Universe Shifter is one of ten completely made up inventions listed on page 54,367 of the Galactic Miscellany. 
NOTES TO THE TEXT
 It is a scientifically proven fact that no one ever deliberately keeps more than two old issues of the Sunday Times Magazine. It has also been scientifically proven that two old issues of the Sunday Times Magazine, left in the dark, quiet place for two months or more, will start absorbing and subtly altering the matter around them in order to create further back issues of the Sunday Times Magazine. Theoretical physicists have calculated that the inevitable end of the universe will come, not in the form of a second Big Bang, but instead when all of the matter of creation has been transformed into back issues of the Sunday Times Magazine. The same physicists have calculated that this day is as little as 10 to the power one hundred and eight million years away, and they further advise that everyone starts recycling now. Before it's too late.
 This idea -- that learning is more efficient when students discover things for themselves -- has become widely accepted in the more progressive regions of the galaxy in recent years, and has led to radical restructuring of teaching methods at many of the established galactic seats of learning, most notably the Hoogle-Floogle University of Being a Right Smart Arse. When students matriculate at the University of Hoogle-Floogle, instead of receiving a reading list or a lecture timetable, they are drugged, blindfolded and abandoned at a randomly selected location somewhere deep inside the Academy's six and half thousand miles of underground library catacombs. Those students who manage to locate the library's single exit in time to for the graduation ceremony three years later will have discovered many things for themselves -- including, in almost all cases, a much lesser aversion to cannibalism than they had going in.
 A picosecond is shorter than a nanosecond, but longer than the time it takes for an unattended iron to ruin a good shirt.
 He was actually right about one of these.
 Ed. Prefect & Dent. Available direct from Megadodo Publications of Ursa Minor Beta, or from most large branches of Waterstones.