Clarke, Arthur C - SSC 04 (11 page)

Grayle was speaking once more in his quiet,
dreamy voice.

‘In that case,’ he said, ‘what you do is
neither good nor bad, for it concerns you alone. If the Wall was built to keep
something from our world, it will still be impassable from the other side.’

Brayldon nodded.

‘We had thought of that,’ he said with a
touch of pride. ‘If the need should come, the ramp can be destroyed in a moment
by explosives at selected spots.’

‘That is good,’ the old man replied. ‘Though
I do not believe those stories, it is well to be prepared. When the work is
finished, I hope I shall still be here. And now I shall try to remember what I
heard of the Wall when I was as young as you were, Shervane, when you first
questioned me about it.’

Before the winter came, the road to the Wall
had been marked out and the foundations of the temporary town had been laid.
Most of the materials Brayldon needed were not hard to find, for the Shadow
Land was rich in minerals. He had also surveyed the Wall itself and chosen the
spot for the stairway. When Trilorne began to dip below the horizon, Brayldon
was well content with the work that had been done.

By the next summer the first of the myriad
concrete blocks had been made and tested to Brayldon’s satisfaction, and before
winter came again some thousands had been produced and part of the foundations
laid. Leaving a trusted assistant in charge of the production, Brayldon could
now return to his interrupted work. When enough of the blocks had been made, he
would be back to supervise the building, but until then his guidance would not
be needed.

Two or three times in the course of every
year, Shervane rode out to the Wall to watch the stockpiles growing into great
pyramids, and four years later Brayldon returned with him. Layer by layer the
lines of stone started to creep up the flanks of the Wall, and the slim
buttresses began to arch out into space. At first the stairway rose slowly, but
as its summit narrowed the increase became more and more rapid. For a third of
every year the work had to be abandoned, and there were anxious months in the
long winter when Shervane stood on the borders of the Shadow Land, listening to
the storms that thundered past him into the reverberating darkness. But
Brayldon had built well, and every spring the work was standing unharmed as
though it would outlive the Wall itself.

The last stones were laid seven years after
the beginning of the work. Standing a mile away, so that he could see the
structure in its entirety, Shervane remembered with wonder how all this had
sprung from the few sketches Brayldon had shown him years ago, and he knew
something of the emotion the artist must feel when his dreams become reality.
And he remembered, too, the day when, as a boy by his father’s side, he had
first seen the Wall far off against the dusky sky of the Shadow Land.

There were guardrails around the upper
platform, but Shervane did not care to go near its edge. The ground was at a
dizzying distance, and he tried to forget his height by helping Brayldon and
the workmen erect the simple hoist that would lift him the remaining twenty
feet. When it was ready he stepped into the machine and turned to his friend
with all the assurance he could muster.

‘I shall be gone only a few minutes,’ he
said with elaborate casualness. ‘Whatever I find, I’ll return immediately.’

He could hardly have guessed how small a
choice was his.

Grayle was now almost blind and would not
know another spring. But he recognised the approaching footsteps and greeted
Brayldon by name before his visitor had time to speak.

‘I am glad you came,’ he said. ‘I’ve been
thinking of everything you told me, and I believe I know the truth at last.
Perhaps you have guessed it already.’

‘No,’ said Brayldon. ‘I have been afraid to
think of it.’

The old man smiled a little.

‘Why should one be afraid of something
merely because it is strange? The Wall is wonderful, yes – but there’s nothing
terrible about it, to those who will face its secret without flinching.

‘When I was a boy, Brayldon, my old master
once said that time could never destroy the truth – it could only hide it among
legends. He was right. From all the fables that have gathered around the Wall,
I can now select the ones that are part of history.

‘Long ago, Brayldon, when the First Dynasty
was at its height, Trilorne was hotter than it is now and the Shadow Land was
fertile and inhabited – as perhaps one day the Fire Lands may be when Trilorne
is old and feeble. Men could go southward as they pleased, for there was no
Wall to bar the way. Many must have done so, looking for new lands in which to
settle. What happened to Shervane happened to them also, and it must have
wrecked many minds – so many that the scientists of the First Dynasty built the
Wall to prevent madness from spreading through the land. I cannot believe that
this is true, but the legend says that it was made in a single day, with no
labour, out of a cloud that encircled the world.’

He fell into a reverie, and for a moment
Brayldon did not disturb him. His mind was far in the past, picturing his world
as a perfect globe floating in space while the Ancient Ones threw that band of
darkness around the equator. False though that picture was in its most important
detail, he could never wholly erase it from his mind.

*

As the last few feet of the Wall moved
slowly past his eyes, Shervane needed all his courage lest he cry out to be
lowered again. He remembered certain terrible stories he had once dismissed with
laughter, for he came of a race that was singularly free from superstition. But
what if, after all, those stories had been true, and the Wall had been built to
keep some horror from the world?

He tried to forget these thoughts, and found
it not hard to do so once he had passed the topmost level of the Wall. At first
he could not interpret the picture his eyes brought him: then he saw that he
was looking across an unbroken black sheet whose width he could not judge.

The little platform came to a stop, and he
noted with half-conscious admiration how accurate Brayldon’s calculations had
been. Then, with a last word of assurance to the group below, he stepped onto
the Wall and began to walk steadily forward.

At first it seemed as if the plain before
him was infinite, for he could not even tell where it met the sky. But he
walked on unfaltering, keeping his back to Trilorne. He wished he could have
used his own shadow as a guide, but it was lost in the deeper darkness beneath
his feet.

There was something wrong: it was growing
darker with every footstep he took. Startled, he turned around and saw that the
disc of Trilorne had now become pale and dusky, as if seen through a darkened
glass. With mounting fear, he realised that this was by no means all that had happened
–
Trilorne was smaller than the sun he had known all his life
.

He shook his head in an angry gesture of
defiance. These things were fancies; he was imagining them. Indeed, they were
so contrary to all experience that somehow he no longer felt frightened but
strode resolutely forward with only a glance at the sun behind.

When Trilorne had dwindled to a point, and
the darkness was all around him, it was time to abandon pretence. A wiser man
would have turned back there and then, and Shervane had a sudden nightmare
vision of himself lost in this eternal twilight between earth and sky, unable
to retrace the path that led to safety. Then he remembered that as long as he
could see Trilorne at all he could be in no real danger.

A little uncertainly now, he continued his
way with many backward glances at the faint guiding light behind him. Trilorne
itself had vanished, but there was still a dim glow in the sky to mark its
place. And presently he needed its aid no longer, for far ahead a second light
was appearing in the heavens.

At first it seemed only the faintest of
glimmers, and when he was sure of its existence he noticed that Trilorne had
already disappeared. But he felt more confidence now, and as he moved onward,
the returning light did something to subdue his fears.

When he saw that he was indeed approaching
another sun, when he could tell beyond any doubt that it was expanding as a
moment ago he had seen Trilorne contract, he forced all amazement down into the
depths of his mind. He would only observe and record: later there would be time
to understand these things. That his world might possess two suns, one shining
upon it from either side, was not, after all, beyond imagination.

Now at last he could see, faintly through
the darkness, the ebon line that marked the Wall’s other rim. Soon he would be
the first man in thousands of years, perhaps in eternity, to look upon the
lands that it had sundered from his world. Would they be as fair as his own,
and would there be people there whom he would be glad to greet?

But that they would be waiting, and in such
a way, was more than he had dreamed.

Grayle stretched his hand out toward the
cabinet beside him and fumbled for a large sheet of paper that was lying upon
it. Brayldon watched him in silence, and the old man continued.

‘How often we have all heard arguments about
the size of the universe, and whether it has any boundaries! We can imagine no
ending to space, yet our minds rebel at the idea of infinity. Some philosophers
have imagined that space is limited by curvature in a higher dimension – I
suppose you know the theory. It may be true of other universes, if they exist,
but for ours the answer is more subtle.

‘
Along the line of the Wall, Brayldon,
our universe comes to an end – and yet does not
. There was no boundary,
nothing to stop one going onward before the Wall was built. The Wall itself is
merely a man-made barrier, sharing the properties of the space in which it
lies. Those properties were always there, and the Wall added nothing to them.’

He held the sheet of paper toward Brayldon
and slowly rotated it.

‘Here,’ he said, ‘is a plain sheet. It has,
of course, two sides.
Can you imagine one that has not?
’

Brayldon stared at him in amazement.

‘That’s impossible – ridiculous!’

‘But is it?’ said Grayle softly. He reached
toward the cabinet again and his fingers groped in its recesses. Then he drew
out a long, flexible strip of paper and turned vacant eyes to the silently
waiting Brayldon.

‘We cannot match the intellects of the First
Dynasty, but what their minds could grasp directly we can approach by analogy.
This simple trick, which seems so trivial, may help you to glimpse the truth.’

He ran his fingers along the paper strip,
then joined the two ends together to make a circular loop.

‘Here I have a shape which is perfectly
familiar to you – the section of a cylinder. I run my finger around the inside,
so – and now along the outside. The two surfaces are quite distinct: you can go
from one to the other only by moving through the thickness of the strip. Do you
agree?’

‘Of course,’ said Brayldon, still puzzled.
‘But what does it prove?’

‘Nothing,’ said Grayle. ‘But now watch—’

*

This sun, Shervane thought, was Trilorne’s
identical twin. The darkness had now lifted completely, and there was no longer
the sensation, which he would not try to understand, of walking across an
infinite plain.

He was moving slowly now, for he had no
desire to come too suddenly upon that vertiginous precipice. In a little while
he could see a distant horizon of low hills, as bare and lifeless as those he
had left behind him. This did not disappoint him unduly, for the first glimpse
of his own land would be no more attractive than this.

So he walked on: and when presently an icy
hand fastened itself upon his heart, he did not pause as a man of lesser
courage would have done. Without flinching, he watched that shockingly familiar
landscape rise around him, until he could see the plain from which his journey
had started, and the great stairway itself, and at last Brayldon’s anxious,
waiting face.

Again Grayle brought the two ends of the
strip together, but now he had given it a half-twist so that the band was
kinked. He held it out to Brayldon.

‘Run your finger around it now,’ he said
quietly.

Brayldon did not do so: he could see the old
man’s meaning.

‘I understand,’ he said. ‘You no longer have
two separate surfaces. It now forms a single continuous sheet –
a one-sided
surface
– something that at first sight seems utterly impossible.’

‘Yes,’ replied Grayle very softly. ‘I
thought you would understand.
A one-sided surface
. Perhaps you realise
now why this symbol of the twisted loop is so common in the ancient religions,
though its meaning has been completely lost. Of course, it is no more than a
crude and simple analogy – an example in two dimensions of what must really
occur in three. But it is as near as our minds can ever get to the truth.’

There was a long, brooding silence. Then
Grayle sighed deeply and turned to Brayldon as if he could still see his face.

‘Why did you come back before Shervane?’ he
asked, though he knew the answer well enough.