The lock only had a few parts that she could observe: the crank, the bolt, and a pair of brass drums set into the top with digits from 0 to 9 engraved in them, so that by spinning different ways, they could display all the integers from 00 to 99. These drums were in almost constant motion whenever the crank was turning.
Nell had managed to detach several yards of chain from the one that she was using to converse with the Duke, and so she was able to feed different messages into the lock and see what result they had.
The number on the top changed with every link that went into the machine, and it seemed to determine, in a limited way, what the machine would do next; for example, she had learned that the number happened to be 09, and if the next link in the chain was in the vertical position (which the Duke referred to as a one), the drums would spin around and change the number to 23. But if the next link was, instead, a zero (as the Duke referred to links with horizontal toggles), the number drums would change to 03. But that wasn't all: In this case, the machine would, for some reason, reverse the direction in which the chain was moving through the machine, and also flick the toggle from zero to one. That is, the machine could write on the chain as well as read from it.
From idle chitchat with the Duke she learned that the numbers on the drums were referred to as states. At first she did not know which states led to other states, and so she wandered aimlessly from one state to the next, recording the connections on scratch paper. This soon grew to a table listing some thirty-two different states and how the lock would respond to a one or a zero when it was in each of those states. It took a while for Nell to fill out all the blank spaces in the table, because some of the states were hard to get to—they could be reached only by getting the machine to write a certain series of ones and zeros on the chain.
She would have gone crazy with ones and zeros were it not for the frequent interruptions from the Duke, who evidently had nothing better to do than to send her messages. These two parallel courses of inquiry occupied all of Nell's free time for a couple of weeks, and she made slow but steady progress.
“You must learn how to operate the lock on your door,” the Duke said. “This will enable you to effect an escape and to come and rescue me. I will instruct you.”
All he wanted to talk about was technology, which wouldn't help Nell in figuring out whether he was a human or a machine. “Why don't you pick your own lock,” she responded, “and come and rescue me? I am just a poor helpless young thing all alone in the world, and so scared and lonely, and you seem so brave and heroic; your story really is quite romantic, and I cannot wait to see how it all comes out now that our fates have become intertwined.”
“The machines placed a special lock on my door, not a Turing machine,” responded the Duke.
“Describe yourself,” Nell wrote.
“Nothing special, I'm afraid,” wrote the Duke. “How about yourself?”
“Slightly taller than average, flashing green eyes, raven hair falling in luxuriant waves to my waist unless I pin it up to emphasize my high cheekbones and full lips. Narrow waist, pert breasts, long legs, alabaster skin that flushes vividly when I am passionate about something, which is frequently.”
“Your description is reminiscent of my late wife, God rest her soul.”
“Tell me about your wife.”
“The subject fills me with such unutterable sadness that I cannot bear to write about it. Now, let's buckle down to work on the Turing machine.”
Since the prurient approach had dead-ended, Nell tried a different tack: playing stupid. Sooner or later, the Duke would become a little testy. But he was always terribly patient with her, even after the twentieth repetition of “Could you explain it again with different words? I still don't get it.” Of course, for all she knew, he was upstairs punching the walls until his knuckles were bloody and simply pretending to be patient with her. A man who'd been locked up in a tower for years would learn to be extremely patient.
She tried sending him poetry. He sent back glowing reviews but declined to send her any of his own, saying it wasn't good enough to be committed to metal.
On her twentieth day in the dungeon, Princess Nell finally got the lock open. Rather than making an immediate escape, she locked herself back in and sat down to ponder her next move.
If the Duke was human, she should notify him so that they could plan their escape. If he was a machine, doing so would lead to disaster. She had to figure out the Duke's identity before she made another move.
She sent him another poem.
For the Greek's love she gave away her heart
Her father, crown and homeland.
They stopped to rest on Naxos
She woke up alone upon the strand
The sails of her lover's ship descending
Round the slow curve of the earth. Ariadne
Fell into a swoon on the churned sand
And dreamed of home. Minos did not forgive her
And holding diamonds in the pouches of his eyes
Had her flung into the Labyrinth.
She was alone this time. Through a wilderness
Of blackness wandered Ariadne many days
Until she tripped on the memory.
It was still wound all through the place.
She spun it round her fingers
Lifted it from the floor
Knotted it into lace
Erased it.
The lace made a gift for him who had imprisoned her.
Blind with tears, he read it with his fingers
And opened his arms.
The answer came back much too quickly, and it was the same answer as always: “I do so envy your skill with words. Now, if you do not object, let us turn our attention to the inner workings of the Turing machine.”
She had made it as obvious as she dared, and the Duke still hadn't gotten the message. He must be a machine.
Why the deception?
Clearly, the mechanical Duke desired for her to learn about the Turing machines. That is, if a machine could ever be said to desire something.
There must be something wrong with the Duke's programming. He knew there was something wrong with it, and he needed a human to fix it.
Once Nell had figured these things out, the rest of the Castle Turing story resolved itself quickly and neatly. She slipped out of her cell and stealthily explored the castle. The soldiers rarely noticed her, and when they did, they could not improvise; they had to go back to the Duke to be reprogrammed. Eventually, Princess Nell found her way into a room beneath the windmill that contained a sort of clutch mechanism. By disengaging the clutch, she was able to stop the Shaft. Within a few hours, the springs inside the soldiers' back had all run down, and they had all stopped in their tracks. The whole castle was frozen, as if she had cast an enchantment over it.
Now roaming freely, she opened up the Duke's throne and found a Turing machine beneath it. On either side of the machine was a narrow hole descending straight through the floor and into the earth for as far as her torch light could illuminate it. The chain containing the Duke's program dangled on either side into these holes. Nell tried throwing stones into the holes and never heard them hit bottom; the chain must be unfathomably long.
High up in one of the castle's towers, Princess Nell found a skeleton in a chair, slumped over a table piled high with books. Mice, bugs, and birds had nibbled away all of the flesh, but traces of gray hair and whiskers were still scattered around the table, and around the cervical vertebrae was a golden chain bearing a seal with the T insignia.
She spent some time going through the Duke's books. Most of them were notebooks where he would sketch the inventions he hadn't had time to build yet. He had plans for whole armies of Turing machines made to run in parallel, and for chains with links that could be set in more than two positions, and for machines that would read and write on two-dimensional sheets of chain mail instead of one-dimensional chains, and for a three-dimensional Turing grid a mile on a side, through whi
ch a mobile Turing machine would climb about, computing as it went.
No matter how complicated his designs became, the Duke always found a way to simulate their behavior by putting a sufficiently long chain into one of the traditional Turing machines. That is to say that while the parallel and multidimensional machines worked more quickly than the original model, they didn't really do anything different.
One afternoon, Nell was sitting in her favorite meadow, reading about these things in the Primer, when a riderless chevaline emerged from the woods and galloped directly toward her. This was not highly unusual, in and of itself; chevalines were smart enough to be sent out in search of specific persons. People rarely sent them in search of Nell, though.
The chevaline galloped at her full-tilt until it was just a few feet away, and then planted its hooves and stopped instantly—a trick it could easily do when it wasn't carrying a human. It was carrying a note written in Miss Stricken's hand: “Nell, please come immediately. Miss Matheson has requested your presence, and time is short.”
Nell didn't hesitate. She gathered her things, stuffed them into the mount's small luggage compartment, and climbed on. “Go!” she said. Then, getting herself well situated and clenching the hand-grips, she added, “Unlimited speed.” Within moments the chevaline was threading gaps between trees at something close to a cheetah's sprint velocity, clawing its way up the hill toward the dog pod grid.
From the way the tubes ran, Nell guessed that Miss Matheson was plugged into the Feed in two or three different ways, though everything had been discreetly hidden under many afghans, piled up on top of her body like the airy layers of a French pastry. Only her face and hands were visible, and looking at them Nell remembered for the first time since their introduction just how old Miss Matheson was. The force of her personality had blinded Nell and all the girls to the blunt evidence of her true age.
“Please let us be, Miss Stricken,” Miss Matheson said, and Miss Stricken backed out warily, strewing reluctant and reproving glances along her trail.
Nell sat on the edge of the bed and carefully lifted one of Miss Matheson's hands from the coverlet, as if it were the desiccated leaf of some rare tree. “Nell,” Miss Matheson said, “do not waste my few remaining moments with pleasantries.”
“Oh, Miss Matheson—” Nell began, but the old lady's eyes widened and she gave Nell a certain look, practiced through many decades in the classroom, that still had not lost its power to silence.
“I have requested that you come here because you are my favorite student. No! Do not say a word,” Miss Matheson admonished her, as Nell leaned her face closer, eyes filling with tears. “Teachers are not supposed to have favorites, but I am approaching that time when I must confess all my sins, so there it is.
“I know that you have a secret, Nell, though I cannot imagine what it is, and I know that your secret has made you different from any other girl I have ever taught. I wonder what you suppose you will do with your life when you leave this Academy, as you must soon, and go out into the world?”
“Take the Oath, of course, as soon as I reach the age of eligibility. And I suppose that I should like to study the art of programming, and how ractives are made. Someday, of course, after I have become one of Her Majesty's subjects, I should like to find a nice husband and perhaps raise children—”
“Oh, stop it,” Miss Matheson said. “You are a young woman—of course you think about whether you shall have children—every young woman does. I haven't much time left, Nell, and we must dispense with what makes you like all the other girls and concentrate on what makes you different.”
At this point, the old lady gripped Nell's hand with surprising force and raised her head just a bit off the pillow. The tremendous wrinkles and furrows on her brow deepened, and her hooded eyes took on an intense burning appearance. “Your destiny is marked in some way, Nell. I have known it since the day Lord Finkle-McGraw came to me and asked me to admit you—a ragged little thete girl—into my Academy.
“You can try to act the same—we have tried to make you the same—you can pretend it in the future if you insist, and you can even take the Oath—but it's all a lie. You are different.”
These words struck Nell like a sudden cold wind of pure mountain air and stripped away the soporific cloud of sentimentality. Now she stood exposed and utterly vulnerable. But not unpleasantly so.
“Are you suggesting that I leave the bosom of the adopted tribe that has nurtured me?”
“I am suggesting that you are one of those rare people who transcends tribes, and you certainly don't need a bosom anymore,” Miss Matheson said. “You will find, in time, that this tribe is as good as any other—better than most, really.” Miss Matheson exhaled deeply and seemed to dissolve into her blankets. “Now, I haven't long. So give us a kiss, and then be on your way, girl.”
Nell leaned forward and pressed her lips against Miss Matheson's cheek, which looked leathery but was surprisingly soft. Then, unwilling to leave so abruptly, she turned her head and rested it on Miss Matheson's chest for a few moments. Miss Matheson stroked feebly at her hair and tut-tutted.
“Farewell, Miss Matheson,” Nell said. “I will never forget you.”
“Nor I you,” Miss Matheson whispered, “though admittedly that is not saying much.”
A very large chevaline stood stolidly in front of Constable Moore's house, somewhere between a Percheron and a small elephant in size and bulk. It was the dirtiest object Nell had ever seen in her life—its encrustations alone must have weighed hundreds of pounds and were redolent with the scent of night soil and stagnant water. A fragment of a mulberry branch, still bearing leaves and even a couple of actual berries, had gotten wedged into a flexing joint between two adjoining armor plates, and long ropes of milfoil trailed from its ankles.
The Constable was sitting in the middle of his bamboo grove, enveloped in a suit of hoplite armor, similarly filthy and scarred, that was twice as big as he was, and that made his bare head look absurdly small. He had ripped the helmet off and dropped it into his fish pond, where it floated around like the eviscerated hull of a scuttled dreadnought. He looked very gaunt and was staring vacantly, without blinking, at some kudzu that was slowly but inexorably conquering the wisteria. As soon as Nell saw the look on his face, she made him some tea and brought it to him. The Constable reached for the tiny alabaster teacup with armored hands that could have crumbled stones like loaves of stale bread. The thick barrels of the guns built into the arms of his suit were scorched on the inside. He plucked the cup from Nell's hands with the precision of a surgical robot, but did not lift it to his lips, perhaps afraid that he might, in his exhaustion, get the distance a bit wrong and inadvertently crush the porcelain into his jaw, or even decapitate himself. Merely holding the cup, watching the steam rise from its surface, seemed to calm him. His nostrils dilated once, then again. “Darjeeling,” he said. “Well chosen. Always thought of India as a more civilised place than China. Have to throw out all of the oolong now, all the keemun, the lung jang, the lapsang souchong. Time to switch over to Ceylon, pekoe, assam.” He chuckled.
White trails of dried salt ran back from the corners of the Constable's eyes and disappeared into his hairline. He had been riding fast with his helmet off. Nell wished that she had been able to see the Constable thundering across China on his war chevaline.
“I've retired for the last time,” he explained. He nodded in the direction of China. “Been doing a bit of consulting work for a gentleman there. Complicated fellow. Dead now. Had many facets, but now he'll go down in history as just another damn Chinese warlord who didn't make the grade. It is remarkable, love,” he said, looking at Nell for the first time, “how much money you can make shovelling back the tide. In the end you need to get out while the getting is good. Not very honourable, I suppose, but then, there is no honour among consultants.”
Nell did not imagine that Constable Moore wanted to get into a detailed discussion of recent events, so she changed the su
bject. “I think I have finally worked out what you were trying to tell me, years ago, about being intelligent,” she said.
The Constable brightened all at once. “Pleased to hear it.”
“The Vickys have an elaborate code of morals and conduct. It grew out of the moral squalor of an earlier generation, just as the original Victorians were preceded by the Georgians and the Regency. The old guard believe in that code because they came to it the hard way. They raise their children to believe in that code—but their children believe it for entirely different reasons.”
“They believe it,” the Constable said, “because they have been indoctrinated to believe it.”
“Yes. Some of them never challenge it—they grow up to be small-minded people, who can tell you what they believe but not why they believe it. Others become disillusioned by the hypocrisy of the society and rebel—as did Elizabeth Finkle-McGraw.”
“Which path do you intend to take, Nell?” said the Constable, sounding very interested. “Conformity or rebellion?”
“Neither one. Both ways are simple-minded—they are only for people who cannot cope with contradiction and ambiguity.”
“Ah! Excellent!” the Constable exclaimed. As punctuation, he slapped the ground with his free hand, sending up a shower of sparks and transmitting a powerful shock through the ground to Nell's feet.
“I suspect that Lord Finkle-McGraw, being an intelligent man, sees through all of the hypocrisy in his society, but upholds its principles anyway, because that is what is best in the long run. And I suspect that he has been worrying about how best to inculcate this stance in young people who cannot understand, as he does, its historical antecedents—which might explain why he has taken an interest in me. The Primer may have been Finkle-McGraw's idea to begin with—a first attempt to go about this systematically.”
“The Duke plays his cards close,” Constable Moore said, “and so I cannot say whether your suppositions are correct. But I will admit it hangs together nicely.”
“Thank you.”