Constancy-of-Purpose was a big, burly woman who habitually wore sleeveless tunics, leaving the huge muscles of her arms exposed. Her face, too, was strong, broad and patient, habitually placid beneath her shaven scalp. The lower half of her body, by contrast, was wasted, spindly, giving her a strangely unbalanced look.

Morrow said to Constancy-of-Purpose, “You always talk to me as if I were still a child.” As, in Constancy-of-Purpose’s eyes, he probably always would be. Constancy-of-Purpose was twenty years older than Morrow, and she had always assumed the role of older mentor — even now, after five centuries of life, when a mere couple of decades could go by barely noticed. The fact that they’d once been married, for a few decades, had made no long-term difference to their relationship at all. “Look, Constancy-of-Purpose, so much of our little world just doesn’t make sense. And it drives me crazy to think about it.”

Constancy-of-Purpose straightened up and rested her fists on her hips; her face gleamed with sweat. “No, it doesn’t.”

“What?”

“It doesn’t drive you crazy. Nobody as old as you — or me — is capable of being driven crazy by anything. We don’t have the energy to be mad any more, Morrow.”

Morrow sighed. “All right. But it ought to drive me crazy. And you. There’s so much that is simply — unsaid.” He hoisted the half-full sack of fruit. “Look at the work we’re doing now, even. This simply isn’t logical.”

“Logical enough. Copafeira sap is a useful fuel. And we need the fruit to supplement the supply machines, which haven’t worked properly since — ”

“Yes,” Morrow said, exasperated, “but where does the fruit come from? Who brings it here, to these Locks? And — ”

“And what?”

“And what do they want with the ratchets, and knives, and figure-of-eight rings we bring them?”

Morrow picked up the sap flagons, and Constancy-of-Purpose slung the fruit bag over her shoulder. They began the hundred-yard walk to the next Lock. Constancy-of-Purpose moved with an uneven, almost waddling motion, her stick-like legs seeming almost too weak to support the massive bulk of her upper body. Some obscure nanobot failure had left her legs shriveled, spindly and — Morrow suspected, though Constancy-of-Purpose never complained — arthritic.

“I don’t know,” said Constancy-of-Purpose simply. “And I don’t think about it.” She looked sideways at Morrow.

“But it doesn’t make sense.” Morrow looked up, nervously, at the bulkhead above him. “This fruit must come from somewhere. There must be people up there, Constancy-of-Purpose — people we’ve never seen, whose existence has never been acknowledged by the Planners, or — ”

“People whose existence doesn’t matter a damn, then.”

“But it does. We trade with them.” He stopped and held out his sack of fruit. “Look at this. We’ve carried on this trade with them — thereby implicitly acknowledging their existence — for decades now.”

Constancy-of-Purpose kept walking, painfully. “Centuries, actually.”

When he was a young man, Morrow had been angry just about the whole time, he recalled. Now — even now — he felt a ghostly surge of that old anger. He felt obscurely proud of himself: a feeling of anger was as rare an event as achieving an erection, these days. “But that means our society is, at its core, slightly insane.”

Constancy-of-Purpose shook her massive head and studied Morrow, a tolerant look on her face. “Keep up that talk, and you’ll spend the rest of your life up here. Or somewhere worse.”

“Just think about it,” Morrow said. “A whole society, laboring under a mass delusion… No wonder they shut down the Virtuals. No wonder they banned kids.”

“But we’re all kept fed. Aren’t we? So it can’t be that crazy.” She smiled, her broad face assuming a look of wisdom. “Humans are a very flawed species, Morrow. We simply don’t seem to be able to act rationally, for very long. This sort of thing — a trade with the nonexistent unknowns upstairs — seems a minor aberration to me.”

Morrow studied her curiously. “You believe that? And I think of me as skeptical.”

Constancy-of-Purpose had reached the next Lock; she dropped her sack and leant against the curving metal wall, her hands resting on her knees. “You know, we have this conversation every few years, my friend.”

Morrow frowned. “Really? Do we?”

“Of course.” Constancy-of-Purpose smiled. “At our age, even doubting becomes a habit. And we never come to any conclusion, and the world goes on. Just as it always has.” She straightened up, cautiously flexing her thin legs. “Come on. Let’s get on with our work.”

With a twist of her huge upper arms Constancy-of-Purpose hauled open the door of the Lock.

Then — instead of stepping forward to gather the food-stuffs — she frowned, and looked at Morrow uncertainly. “…I don’t understand.”

“What is it?”

“Look.”

The Lock was empty.

Morrow stared at Constancy-of-Purpose, and then into the empty chamber. He couldn’t take in what he was seeing. These trades had never gone wrong before.

“The knives have gone,” he said.

“We left them here yesterday.”

“But there’s no meat.”

“But the scratches clearly said the knives were what they wanted…”

This dialogue went on for perhaps five minutes. Part of Morrow was able to step outside — to look at himself and Constancy-of-Purpose with a certain detachment, even with pity. Here were two old people, too hopelessly habit-bound to respond to the unexpected.

Constancy-of-Purpose is right. I’ve become like a machine, he thought with anger and sadness. Worse than a machine.

Constancy-of-Purpose said, “I’ll go in and check the markings. Maybe we made some mistake.”

“We never made a mistake before. How could we?”

“I’ll go check anyway.”

Constancy-of-Purpose stepped forward into the Lock and peered up, squinting, at the trade markings.

…And the hatch at the top of the Lock, twenty feet above Constancy-of Purpose’s head, started to open.

Inside the plasma sea, time held little meaning for Lieserl.

As she sank into the Sun she’d abandoned all her Virtual senses, save for sight and a residual body awareness; drifting through the billowing, cloudy plasma was like a childhood vision of sleep, or an endless, oceanic meditation. She’d slowed the clocks which governed her awareness, and allowed herself to slip into long periods of true “sleep” — of unawareness, when she drifted with only her autonomic systems patiently functioning.

And she had allowed, without regret, the crucial link of synchronization between her sensorium and the Universe outside to be severed. While she had drifted around the core of the Sun, sinking almost imperceptibly deeper into its heart, dozens of centuries had worn away on the worlds of mankind…

Here came the photino structure again.

This time she was ready. She strained at the structure as it passed her, every sense open.

Still, she could barely make it out; it was like a crude charcoal sketch against the glowing plasma background.

Wistfully she watched the photino cloud soar out of sight once more, passing through the plasma as if it were no more substantial than mist, on its minutes long orbit around the Sun.

But -

But, had it diverged from its orbit as it passed her? Was it possible that the photino object had actually reacted to her presence?

Now she became aware of more motion, below and ahead of her. The moving forms were shadowy, infuriatingly elusive against the gleaming, almost featureless background. Frustrated, she strained at her senses, demanding that her aged processors extract every last bit of information content from the data they were receiving.