On this particular Thursday, something was moving quietly through the ionosphere many miles above the surface of the planet; several somethings in fact, several dozen huge yellow chunky slablike somethings, huge as office buildings, silent as birds. They soared with ease, basking in electromagnetic rays from the star Sol, biding their time, grouping, preparing.

The planet beneath them was almost perfectly oblivious of their presence, which was just how they wanted it for the moment. The huge yellow somethings went unnoticed at Goonhilly, they passed over Cape Canaveral without a blip, Woomera and Jodrell Bank looked straight through them—which was a pity because it was exactly the sort of thing they’d been looking for all these years.

The only place they registered at all was on a small black device called a Sub-Etha Sens-O-Matic which winked away quietly to itself. It nestled in the darkness inside a leather satchel which Ford Prefect wore habitually round his neck. The contents of Ford Prefect’s satchel were quite interesting in fact and would have made any Earth physicist’s eyes pop out of his head, which is why he always concealed them by keeping a couple of dog-eared scripts for plays he pretended he was auditioning for stuffed in the top. Besides the Sub-Etha Sens-O-Matic and the scripts he had an Electronic Thumb—a short squat black rod, smooth and matt with a couple of flat switches and dials at one end; he also had a device which looked rather like a largish electronic calculator. This had about a hundred tiny flat press buttons and a screen about four inches square on which any one of a million “pages” could be summoned at a moment’s notice. It looked insanely complicated, and this was one of the reasons why the snug plastic cover it fitted into had the words Don’t Panic printed on it in large friendly letters. The other reason was that this device was in fact that most remarkable of all books ever to come out of the great publishing corporations of Ursa Minor—The Hitchhiker’s Guide to the Galaxy. The reason why it was published in the form of a micro sub meson electronic component is that if it were printed in normal book form, an interstellar hitch hiker would require several inconveniently large buildings to carry it around in.

Beneath that in Ford Prefect’s satchel were a few biros, a notepad, and a largish bath towel from Marks and Spencer.

The Hitchhiker’s Guide to the Galaxy has a few things to say on the subject of towels.

A towel, it says, is about the most massively useful thing an interstellar hitch hiker can have. Partly it has great practical value—you can wrap it around you for warmth as you bound across the cold moons of Jaglan Beta; you can lie on it on the brilliant marble-sanded beaches of Santraginus V, inhaling the heady sea vapours; you can sleep under it beneath the stars which shine so redly on the desert world of Kakrafoon; use it to sail a mini raft down the slow heavy river Moth; wet it for use in hand-to-hand-combat; wrap it round your head to ward off noxious fumes or to avoid the gaze of the Ravenous Bugblatter Beast of Traal (a mindboggingly stupid animal, it assumes that if you can’t see it, it can’t see you—daft as a bush, but very ravenous); you can wave your towel in emergencies as a distress signal, and of course dry yourself off with it if it still seems to be clean enough.

More importantly, a towel has immense psychological value. For some reason, if a strag (strag: non-hitch hiker) discovers that a hitch hiker has his towel with him, he will automatically assume that he is also in possession of a toothbrush, face flannel, soap, tin of biscuits, flask, compass, map, ball of string, gnat spray, wet weather gear, space suit etc., etc. Furthermore, the strag will then happily lend the hitch hiker any of these or a dozen other items that the hitch hiker might accidentally have “lost”. What the strag will think is that any man who can hitch the length and breadth of the galaxy, rough it, slum it, struggle against terrible odds, win through, and still knows where his towel is is clearly a man to be reckoned with.

Hence a phrase which has passed into hitch hiking slang, as in “Hey, you sass that hoopy Ford Prefect? There’s a frood who really knows where his towel is.” (Sass: know, be aware of, meet, have sex with; hoopy: really together guy; frood: really amazingly together guy.)

Nestling quietly on top of the towel in Ford Prefect’s satchel, the Sub-Etha Sens-O-Matic began to wink more quickly. Miles above the surface of the planet the huge yellow somethings began to fan out. At Jodrell Bank, someone decided it was time for a nice relaxing cup of tea.

“You got a towel with you?” said Ford Prefect suddenly to Arthur.

Arthur, struggling through his third pint, looked round at him.

“Why? What, no… should I have?” He had given up being surprised, there didn’t seem to be any point any longer.

Ford clicked his tongue in irritation.

“Drink up,” he urged.

At that moment the dull sound of a rumbling crash from outside filtered through the low murmur of the pub, through the sound of the jukebox, through the sound of the man next to Ford hiccupping over the whisky Ford had eventually bought him.

Arthur choked on his beer, leapt to his feet.

“What’s that?” he yelped.

“Don’t worry,” said Ford, “they haven’t started yet.”

“Thank God for that,” said Arthur and relaxed.

“It’s probably just your house being knocked down,” said Ford, drowning his last pint.

“What?” shouted Arthur. Suddenly Ford’s spell was broken. Arthur looked wildly around him and ran to the window.

“My God they are! They’re knocking my house down. What the hell am I doing in the pub, Ford?”

“It hardly makes any difference at this stage,” said Ford, “let them have their fun.”

“Fun?” yelped Arthur. “Fun!” He quickly checked out of the window again that they were talking about the same thing.

“Damn their fun!” he hooted and ran out of the pub furiously waving a nearly empty beer glass. He made no friends at all in the pub that lunchtime.

“Stop, you vandals! You home wreckers!” bawled Arthur. “You half crazed Visigoths, stop will you!”

Ford would have to go after him. Turning quickly to the barman he asked for four packets of peanuts.

“There you are sir,” said the barman, slapping the packets on the bar, “twenty-eight pence if you’d be so kind.”

Ford was very kind—he gave the barman another five—pound note and told him to keep the change. The barman looked at it and then looked at Ford. He suddenly shivered: he experienced a momentary sensation that he didn’t understand because no one on Earth had ever experienced it before. In moments of great stress, every life form that exists gives out a tiny sublimal signal. This signal simply communicates an exact and almost pathetic sense of how far that being is from the place of his birth. On Earth it is never possible to be further than sixteen thousand miles from your birthplace, which really isn’t very far, so such signals are too minute to be noticed. Ford Prefect was at this moment under great stress, and he was born 600 light years away in the near vicinity of Betelgeuse.

The barman reeled for a moment, hit by a shocking, incomprehensible sense of distance. He didn’t know what it meant, but he looked at Ford Prefect with a new sense of respect, almost awe.

“Are you serious, sir?” he said in a small whisper which had the effect of silencing the pub. “You think the world’s going to end?”

“Yes,” said Ford.

“But, this afternoon?”

Ford had recovered himself. He was at his flippest.

“Yes,” he said gaily, “in less than two minutes I would estimate.”