In truly complex systems, how adjustments occur lay beyond the human complexity horizon, beyond knowing—and most important, not worth knowing.

 But if the system went awry, somebody had to get down in the guts of it and find the trouble. “Any ideas? Clues?”

 Yugo shrugged. “Look at this.”

 The fluids lapped at the walls of the bottles. More warped volumes appeared, filled with brightly colored data-liquids. Hari watched as tides swept through the burnt-orange variable-space, driving answering waves in the purple layers nearby. Soon the entire holo showed furiously churning turbulence.

 “So the equations fail,” Hari said.

 “Yeah, big time, too. The grand cycles last about a hundred and twenty-five years. But smoothing out events shorter than eighty years gives a steady pattern. See—”

 Hari watched turbulence build like a hurricane churning a multi­ colored ocean.

 Yugo said, “That takes away scatter due to ‘generational styles,’ Dors calls it. I can take the Zones that consciously increased human lifespan. I time-step the equations forward, great—but then I run out of data. How come? I mine the history some, and it turns out those societies didn’t last long.”

 Hari shook his head. “You’re sure? I’d imagine increasing the average age would bring a little wisdom into the picture.”

 “Not so! I looked deeper and found that when the lifespan reached the social cycle time, usually about a hundred and ten Standard Years, instability rose. Whole planets had wars, depres­ sions, general social illnesses.”

 Hari frowned. “That effect—is it known?”

 “Don’t think so.”

 “This is why humans reached a barrier in improving their longevity? Society breaks down, ending the progress?”

 “Yeah.”

 Yugo wore a small, tight smile, by which Hari knew that he was rather proud of this result. “Growing irregularities, building to—chaos.”

 This was the deep problem they had not mastered. “Damn!” Hari had a gut dislike of unpredictability.

 Yugo gave Hari a crooked smile. “On that one, boss, I got no news.”

 “Don’t worry,” Hari said cheerfully, though he didn’t feel it. “You’ve made good progress. Remember the adage—the Imperium wasn’t built in a day.”

 “Yeah, but it seems to be fallin’ apart plenty fast.”

 They seldom mentioned the deep-seated motivation for psycho­ history: the pervasive anxiety that the Empire was declining, for reasons no one knew. There were theories aplenty, but none had predictive power. Hari hoped to supply that. Progress was infuriat­ ingly slow.

 Yugo was looking morose. Hari got up, came around the big desk, and gave Yugo a gentle slap on the back. “Cheer up! Publish this result.”

 “Can I? We’ve got to keep psychohistory quiet.”

 “Just group the data, then publish in a journal devoted to analyt­ ical history. Talk to Dors about selecting the journal.”

 Yugo brightened. “I’ll write it up, show you—”

 “No, leave me out of it. It’s your work.”

 “Hey, you showed me how to set up the analysis, where—”

 “It’s yours. Publish.”

 “Well…”

 Hari did not mention the fact that, now, anything published under his name would attract attention. A few might guess at the immensely larger theory lurking behind the simple lifespan-resonance effect. Best to keep a low profile.

 When Yugo had gone back to work, Hari sat for a while and watched the squalls work through the data-fluids, still time-stepping in the air above his desk. Then he glanced at a favorite quotation of his, pointed out to him by Dors, given to him on a small, elegant ceramo-plaque: Minimum force, applied at a cusp moment at the histor­ ical fulcrum, paves the path to a distant vision. Pursue only those immediate goals which serve the longest perspectives. —Emperor Kamble’s 9th Oracle, Verse 17

 “But suppose you can’t afford long perspectives?” he muttered, then went back to work.

 7.

 The next day he got an education in the realities of Imperial politics.

 “You didn’t know the 3D scope was on you?” Yugo asked.

 Hari watched the conversation with Lamurk replay on his office holo. He had fled to the University when the Imperial Specials started having trouble holding the media mob away from his apartment. They had called in reinforcements when they caught a team drilling an acoustic tap into the apartment from three layers above. Hari and Dors had gotten out with an escort through a maintenance grav drop.

 “No, I didn’t. There was a lot going on.” He remembered his bodyguards accosting someone, checking and letting it pass. The 3D camera and acoustic tracker were so small that a media deputy could walk around with them under formal wear. Assassins used the same artful concealment. Bodyguards knew how to distinguish between the two.

 Yugo said with Dahlite savvy, “Gotta watch ’em, you gonna play in those leagues.”

 “I appreciate the concern,” Hari said dryly.

 Dors tapped a finger to her lips. “I think you came over rather well.”

 “I didn’t want to seem as though I were deliberately cutting up a majority leader from the High Council,” Hari said heatedly.

 “But that’s what you were doin’,” Yugo said.

 “I suppose, but at the time it seemed like polite…banter,” he fin­ ished lamely. Edited for 3D, it was a quick verbal Ping-Pong with razor blades instead of balls.

 “But you topped him at every exchange,” Dors observed.

 “I don’t even dislike him! He has done good things for the Em­ pire.” He paused, thinking. “But it was…fun.”

 “Maybe you do have a talent for this,” she said.

 “I’d rather not.”

 “I don’t think you have much choice,” Yugo said. “You’re gettin’ famous.”

 “Fame is the accumulation of misunderstandings around a well-known name,” Dors said.

 Hari smiled. “Well put.”

 “It’s from Eldonian the Elder, the longest-lived emperor. The only one of his clan to die of old age.”

 “Makes the point,” Yugo said. “You gotta expect some stories, gossip, mistakes.”

 Hari shook his head angrily. “No! Look, we can’t let this ex­ traneous matter distract us. Yugo, what about those bootleg per­ sonality constellations you ‘acquired’?”

 “I’ve got ’em.”

 “Machine translated? They will run?”

 “Yeah, but they take an awful lot of memory and running volume. I’ve tuned them some, but they need a bigger parallel-processing network than I can give them.”

 Dors frowned. “I don’t like this. These aren’t just constellations, they’re sims.”

 Hari nodded. “We’re doing research here, not trying to manufac­ ture a superrace.”

 Dors stood and paced energetically. “The most ancient of taboos is against sims. Even personality constellations obey rigid laws!”

 “Of course, ancient history. But—”

 “Prehistory.” Her nostrils flared. “The prohibitions go back so far, there are no records of how they started—undoubtedly, from some disastrous experiments well before the Shadow Age.”

 “What’s that?” Yugo asked.

 “The long time—we have no clear idea of how long it lasted, though certainly several millennia—before the Empire became co­ herent.”

 “Back on Earth, you mean?” Yugo looked skeptical.

 “Earth is more legend than fact. But yes, the taboo could go back that far.”

 “These are hopelessly constricted sims,” Yugo said. “They don’t know anything about our time. One is a religious fanatic for some faith I never heard of. The other’s a smartass writer. No danger to anybody, except maybe themselves.”

 Dors regarded Yugo suspiciously. “If they’re so narrow, why are they useful?”

 “Because they can calibrate psychohistorical indices. We have modeling equations that depend on basic human perceptions. If we have a pre-ancient mind, even simmed, we can calibrate the missing constants in the rate equations.”

 Dors snorted doubtfully. “I don’t follow the mathematics, but I know sims are dangerous.”

 “Look, nobody savvy believes that stuff any more,” Yugo said. “Mathists have been running pseudo-sims for ages. Tiktoks—”

 “Those are incomplete personalities, correct?” Dors asked severely.

 “Well, yeah, but—”

 “We could get into very big trouble if these sims are better, more versatile.”

 Yugo waved away her point with his large hands, smiling lazily. “Don’t worry. I got them all under control. Anyway, I’ve already got a way to solve our problem of getting enough running volume, machine time—and I’ve got a cover for us.”

 Hari arched his eyebrows. “What’s this?”

 “I’ve got a customer for the sims. Somebody who’ll run them, cover all expenses, and pay for the privilege. Wants to use them for commercial purposes.”

 “Who?” Hari and Dors asked together.

 “Artifice Associates,” Yugo said triumphantly.

 Hari looked blank. Dors paused as though searching for a distant memory, and then said, “A firm engaged in computer systems ar­ chitecture.”

 “Right, one of the best. They’ve got a market for old sims as en­ tertainment.”

 Hari said, “Never heard of them.”

 Yugo shook his head in amazement. “You don’t keep up, Hari.”

 “I don’t try to keep up. I try to stay ahead.”

 Dors said, “I don’t like using any outside agency. And what’s this about paying?”

 Yugo beamed. “They’re paying for license rights. I negotiated it all.”

 “Do we have any control over how they use the sims?” Dors leaned forward alertly.

 “We don’t need any,” Yugo said defensively. “They’ll probably use them in advertisements or something. How much use can you get out of a sim nobody will probably understand?”

 “I don’t like it. Aside from the commercial aspects, it’s risky to even revive an ancient sim. Public outrage—”

 “Hey, that’s the past. People don’t feel that way about tiktoks, and they’re getting pretty smart.”

 Tiktoks were machines of low mental capacity, held rigorously beneath an intelligence ceiling by the Encoding Laws of antiquity. Hari had always suspected that the true, ancient robots had made those laws, so that the realm of machine intelligence did not spawn ever more specialized and unpredictable types.

 The true robots, such as R. Daneel Olivaw, remained aloof, cool, and long-visioned. But in the gathering anxieties across the entire Empire, traditional cybernetic protocols were breaking down. Like everything else.

 Dors stood. “I’m opposed. We must stop this at once.”

 Yugo rose too, startled. “You helped me find the sims. Now you—”

 “I did not intend this.” Her face tightened.

 Hari wondered at her intensity. Something else was at stake here, but what? He said mildly, “I see no reason to not make a bit of profit from side avenues of our research. And we do need increased computing capacity.”

 Dors’ mouth worked with irritation, but she said nothing more. Hari wondered why she was so opposed. “Usually you don’t give a damn about social conventions.”

 She said acidly, “Usually you are not a candidate for First Minis­ ter.”

 “I will not let such considerations deflect our research,” he said firmly. “Understand?”

 She nodded and said nothing. He instantly felt like an overbearing tyrant. There was always a potential conflict between being coworkers and lovers. Usually they waltzed around the problems. Why was she so adamant?

 They got through some more work on psychohistory, and Dors mentioned his next appointment. “She’s from my history depart­ ment. I asked her to look into patterns in Trantorian trends over the last ten millennia.”

 “Oh, good, thanks. Could you show her in, please?”

 Sylvin Thoranax was a striking woman, bearing a box of old data pyramids. “I found these in a library halfway around the planet,” she explained.

 Hari picked one up. “I’ve never seen one of these. Dusty!”