byTerryPratchett

Teppic had expected--
-- what?
Possibly the splat of flesh hitting rock. Possibly, although this was on the very edge of expectation, the sight of the Old kingdom spread out below him.
He hadn't expected chilly, damp mists.
It is not known to science that there are many more dimensions than the classical four. Scientists say that these don't normally impinge on the world because the extra dimensions are very small and curve in on themselves, and that since reality is fractal most of it is tucked inside itself. This means either that the universe is more full of wonders than we can understand or, more probably, that scientists make things up as they go along.
But the multiverse is full of little dimensionettes, playstreets of creation where creatures of the imagination can romp without being knocked down by serious actuality. Sometimes, as they drift through the holes in reality, they impinge back on this universe, when they give rise to myths, legends and charges of being Drunk and Disorderly.
And it was into one of these that (the camel) You Bastard, by a trivial miscalculation, had trotted.
Legend has got it nearly right. The Sphinx did lurk on the borders of the kingdom. The legend just hadn't been precise about what kind of borders it was talking about.
The sphinx is an unreal creature. It exists solely because it has been imagined. It is well-known that in an infinite universe everything that can be imagined must exist somewhere, and since many of them are not things that ought to exist in a well-ordered space-time frame they get shoved into a side dimension. This may go some way to explaining the Sphinx's chronic bad temper, although any creature created with the body of a lion, bosom of a woman and wings of an eagle has a serious identity crisis and doesn't need much to make it angry.
So it had devised the Riddle.
Across various dimensions it had provided the Sphinx with considerable entertainment and innumerable meals.
This was not known to Teppic as he led You Bastard through the swirling mists, but the bones he crunched underfoot gave him enough essential detail.
A lot of people had died here. And it was reasonable to assume that the more recent ones had seen the remains of the earlier ones, and would therefore have proceed stealthily.
And that hadn't worked.
No sense in creeping along, then. Besides, some of the rocks that loomed out of the mists had a very distressing shape. This one here, for example, looked exactly like-
'Halt,' said the Sphinx.
There was no sound but the drip of the mist and the occasional sucking noise of You Bastard trying to extract moisture from the air.
'You're a sphinx,' said Teppic.
'The Sphinx,' corrected the Sphinx.
'Gosh. We've got any amount of statues to you at home.'
Teppic looked up, and then further up. 'I thought you'd be smaller,' he added.
'Cower, mortal,' said the Sphinx. 'For thou art in the presence of the wise and the terrible.' It blinked. 'Any good, these statues?'
'They don't do you justice,' said Teppic, truthfully.
'Do you really think so? People often get the nose wrong,' said the Sphinx. 'My right profile is best, I'm told, and-'
It dawned on the Sphinx that it was sidetracking itself. It coughed sternly.
'Before you can pass me, O mortal,' it said, 'you must answer my riddle.'
'Why?' said Teppic.
'What?' The Sphinx blinked at him. It hadn't been designed for this sort of thing.
'Why? Why? Because. Er. Because, hang on, yes, because I will bite your head off if you don't. Yes, I think that's it.'
'Right,' said Teppic. 'Let's hear it, then.'
The Sphinx cleared its throat with a noise like an empty lorry reversing in a quarry.
'What goes on four legs in the morning, two legs at noon, and three legs in the evening?' said the Sphinx smugly.
Teppic considered this.
'That's a tough one,' he said, eventually.
'The toughest,' said the Sphinx.
'Um.'
'You'll never get it.'
'Ah,' said Teppic.
'Could you take your clothes off while you're thinking? The threads play merry hell with my teeth.'
'There isn't some kind of animal that regrows legs that have been-'
'Entirely the wrong track,' said the Sphinx, stretching its claws.
'Oh.'
'You haven't got the faintest idea, have you?'
'I'm still thinking,' said Teppic.
'You'll never get it.'
'You're right.' Teppic stared at the claws. This isn't really a fighting animal, he told himself reassuringly, it's definitely over-endowed. Besides, its bosom will get in the way, even if its brain doesn't.
'The answer is: "A Man",' said the Sphinx. 'Now, don't put up a fight, please, it releases unpleasant chemicals into the bloodstream.'
Teppic backed away from a slashing paw. 'Hold on, hold on,' he said. 'What do you mean, a man?'
'It's easy,' said the Sphinx. , A baby crawls in the morning, stands on both legs at noon, and at evening an old man walks with a stick. Good, isn't it?'
Teppic bit his lip. 'We're talking about one day here?' he said doubtfully. There was a long, embarrassing silence.
'It's a wossname, a figure of speech,' said the Sphinx irritably, making another lunge.
'No, no, look, wait a minute,. said Teppic. 'I'd like us to be very clear about this, right? I mean, it's only fair, right?'
'Nothing wrong with the riddle,' said the Sphinx. 'Damn good riddle. Had that riddle for fifty years, sphinx and cub.'
It thought about this. 'Chick,' it corrected.
'It's a good riddle,' Teppic said soothingly. 'Very deep. Very moving. The whole human condition in a nutshell. But you've got to admit, this doesn't all happen to one individual in one day, does it?'
'Well. No,' the Sphinx admitted. 'But that is self-evident from the context. An element of dramatic analogy is present in all riddles,' it added, with the air of one who had heard the phrase a long time ago and rather liked it, although not to the extent of failing to eat the originator.
'Yes, but,' said Teppic crouching down and brushing a clear space on the damp sand, 'is there internal consistency within the metaphor? Let' s say for example that the average life expectancy is seventy years, okay?'
'Okay,' said the Sphinx, in the uncertain tones of someone who has let the salesman in and is now regretfully contemplating a future in which they are undoubtedly going to buy life insurance.
'Right. Good. So noon would be age 35, am I right?. Now considering that most children can toddle at a year or so, the four legs reference is really unsuitable, wouldn't you agree? I mean, most of the morning is spent on two legs. According to your analogy-' he paused and did a few calculations with a convenient thighbone- 'only about twenty minutes immediately after 00.00 hours, half an hour tops, is spent on four legs. Am I right? Be fair.'
'Well-' said the Sphinx.
'By the same token you wouldn't be using a stick by six p.m. because you'd be only, er, 52,' said Teppic, scribbling furiously. 'In fact you wouldn't really be looking at any kind of walking aid until at least half past nine, I think. That's on the assumption that the entire lifespan takes place over one day which is, I believe I have already pointed out, ridiculous. I'm sorry it's basically okay, but it doesn't work.'
'Well,' said the Sphinx, but irritably this time, I don't see what I can do about it. I haven't got any more. It's the only one I've ever needed.'
'You just need to alter it a bit, that's all.'
'How do you mean?'
'Just make it a bit more realistic.'
'Hmm.' The Sphinx scratched its mane with a claw.
'Okay it said doubtfully. 'I suppose I could ask: What is it that walks on four legs-'
'Metaphorically speaking,' said Teppic.
'Four legs metaphorically speaking,' the Sphinx agreed, for about-'
'Twenty minutes, I think we agreed.'
'-okay, fine, twenty minutes in the morning, on two legs-'
'But I think calling it in ''the morning'' is stretching it a bit, said Teppic. 'It's just after midnight. I mean technically it's the morning but in a very real sense its still last night what do you think?'
A look of glazed panic crossed the Sphinx' s face.
'What do you think?' it managed.
'Let's just see where we've got to, shall we? What, metaphorically speaking walks on four legs just after midnight, on two legs for most of the day-'
'-barring accidents,' said the Sphinx, pathetically eager to show that it was making a contribution.
'Fine, on two legs barring accidents, until at least supper-time, when it walks with three legs—'
'I've known people use two walking sticks,' said the Sphinx helpfully.
'Okay. How about: when it continues to walk on two legs or with any prosthetic aids of its choice?'
The Sphinx gave this some consideration.
'Ye-ess,' it said gravely. 'That seems to fit all eventualities.'
'Well?' said Teppic.
'Well what?' said the Sphinx.
'Well, what's the answer?'
The Sphinx gave him a stony look, and then showed its fangs.
'Oh no,' it said. 'You don't catch me out like that. You think I'm stupid? You've got to tell me the answer.'
'Oh, blow,' said Teppic.
'Thought you had me there, didn't you?' said the Sphinx.
'Sorry.'
'You thought you could get me all confused, did you?'
The Sphinx grinned.
'It was worth a try,' said Teppic.
'Can't blame you. So what's the answer, then?'
Teppic scratched his nose.
'Haven't a clue,' he said. 'Unless, and this is a shot in the dark, you understand, it's: A Man.'
The Sphinx glared at him.
'You've been here before, haven't you?' it said accusingly.
'No.'
'Then someone's been talking. right?'
'Who could have talked? Has anyone ever guessed the riddle?' said Teppic.
'No!'
'Well, then. They couldn't have talked, could they?'
The Sphinx's claws scrabbled irritably on its rock.
'I suppose you'd better move along, then.' it grumbled.
'Thank you,' said Teppic.
'I'd be grateful if you didn't tell anyone, please,' added the Sphinx, coldly. 'I wouldn't like to spoil it for other people.'
Teppic scrambled up a rock and on to You Bastard.
'Don't you worry about that,' he said, spurring the camel onwards. He couldn't help noticing the way the Sphinx was moving its lips silently, as though trying to work something out.
You Bastard had gone only twenty yards or so before an enraged bellow erupted behind him. For once he forgot the etiquette that says a camel must be hit with a stick before it does anything. All four feet hit the sand and pushed.
This time he got it right.