“That’s a sensitive issue. Our clients are told that a perfect match has been found for them. And it’s true. But that isn’t to say we couldn’t find an equally perfect match for them tomorrow, or next month. Except in the case of the supercouples, of course — those really are perfect. But we don’t tell our clients about degrees of perfection, because that might encourage window shopping. Once we’ve found a match, that’s it. End of story. Their avatars are removed from the Tank.”

“And then?”

“The two candidates are notified of the match. A meeting is set up.” As she said this, her expression once again grew distant.

Lash turned to the Tank, staring at the thousands of avatars gliding back and forth within, weightless and alien. “You mentioned the need for computing horsepower,” he murmured. “That seems an understatement. I didn’t know any computer could handle such a job.”

“Funny you should say that.” It was Mauchly speaking this time, slipping the phone back into his jacket pocket. “Because there’s one person in this building who knows more than anyone else about that. And he’s just asked to make your acquaintance.”

Five minutes brought them to a sky lobby: a two-story space on the thirtieth floor, surrounded by banks of elevators. One end opened onto an employee cafeteria, and Lash could see workers clustered around dozens of tables, talking and eating.

“We have ten cafeterias here on the inside,” Mauchly said. “We discourage people from leaving the building for lunch or dinner, and the excellent free food helps.”

“Lunch or dinner?”

“Or breakfast, for that matter. We’ve got technicians working shifts round the clock, especially in the data-gathering sections.” Mauchly made for an elevator at the end of the nearest bank. It was set apart from the others, and a guard in a beige jumpsuit was posted before it. When the guard saw them approach, he stepped aside.

Mauchly turned to Tara. “You’ve got the latest code. Go ahead.” And he indicated a keypad beside the elevators.

“Where are we headed?” Tara asked.

“The penthouse.”

There was a quick intake of breath, quickly checked. Tara punched in a code and, a moment later, the doors opened.

As he stepped inside the elevator, Lash sensed something was different. It wasn’t the walls, which had the same glossy wood grain as the others in the building; it wasn’t the carpeting, or the lighting, or the safety railing. Suddenly he realized what it was. There was no pinhole security camera in this car. And there were only three buttons on the instrument panel, all unmarked. Mauchly pressed the topmost button, placed his bracelet beneath the scanner.

The elevator rose for what seemed forever. At last it opened onto a brilliantly lit room. But this was not the artificial light Lash had seen elsewhere in Eden: this was sunlight, streaming in from windows that filled three of the four walls. He stepped forward onto a sumptuous blue carpet, looking around in wonder. Through the wall of glass, the dense cityscape of mid-Manhattan lay beneath a cloudless sky. To his left, and right — at what seemed great distances — other windows afforded unbroken vistas of Long Island and New Jersey. Instead of the fluorescent lighting panels of the floors below, beautiful cut-glass fixtures hung from the ceiling, unnecessary in this explosion of daylight.

Lash remembered seeing, from street level, the figured grille that set off the tower’s topmost floors. And he recalled Mauchly’s words: The tower is made up of three separate buildings. Atop the inner tower is the penthouse. This aerie that crowned the corporate tower could only be one thing: the lair of its reclusive founder, Richard Silver.

Except for the elevator door, the entire fourth wall was covered in rich mahogany bookcases. But they were not the leather-bound volumes one would expect in such a setting; there were cheap science fiction paperbacks, yellowing and broken-backed; technical journals, clearly well thumbed; oversize manuals for computer operating systems and languages.

Tara Stapleton had walked across the wide floor and was staring at something before one of the windows. As his eyes grew used to the light, Lash became aware that dozens of objects — some large, some small — were arranged in front of the huge plates of glass. He stepped forward himself, curious, stopping before a contraption almost the size of a telephone booth. Rising from its wooden base was a complex architecture of rotors, stacked horizontally on spars of metal. Behind the rotors was a complex nesting of wheels, rods, and levers.

He moved to the next window, where what looked like the metal guts of some giant’s music box lay on a wooden stand. Beside it was a monstrous device: a cross between an ancient printing press and a grandfather clock. A large metal crank was visible on one side, and its face was covered with flat, polished metal discs of all sizes. Large spools of paper sat on a wooden tray between its legs.

Mauchly seemed to have disappeared, but another man was approaching them from across the room: tall, youthful-looking, with a vast mop of red hair rising from a square forehead. He was smiling, and his watery blue eyes peered out through thin silver frames with a friendly sparkle. He wore a tropical shirt over a pair of worn jeans. Though Lash had never seen the man before, he instantly recognized him: Richard Silver, the genius behind both Eden and the computer that made it possible.

“You must be Dr. Lash,” the man said, extending his hand. “I’m Richard Silver.”

“Call me Christopher,” Lash said.

Silver turned toward Tara, who had turned wordlessly at the man’s approach. “And you’re Tara Stapleton? Edwin’s told me great things about you.”

“It’s an honor to meet you, Dr. Silver,” she replied.

Lash listened to this exchange in surprise. She’s the chief security tech. But she’s never met him before.

Silver turned back to Lash. “Your name rings a bell, Christopher, but I can’t quite place it.”

Lash said nothing, and after a moment, Silver shrugged. “Ah, well. Perhaps it will return to me. In any case, I’m curious about your theoretical orientation. Given your prior job, I’d guess you belong to the cognitive behavioral school?”

This was the last thing Lash expected to hear. “More or less. I’m eclectic, I like to pick and choose from other schools as well.”

“I see. Such as behavioral? Humanist?”

“More the former than the latter, Dr. Silver.”

“It’s Richard, please.” Silver smiled again. “You’re right to pick and choose. Cognitive behavioral psychology has always been fascinating to me because it lends itself to information processing. But on the other hand, strict behaviorists feel all behavior is learned. Right?”

Lash nodded, surprised. Silver did not fit his image of what a brilliant recluse should look like.

“You’ve got a remarkable collection here,” he said.

“My little museum. These devices are my one weakness. Such as that beauty you were just examining: Kelvin’s Tide Predictor. It could predict the high and low tides for any future date. And note the paper drums at its base: perhaps the first instance of hardcopy output. Or how about the device on the stand beside it? Built more than three hundred and fifty years ago, but it can still do all the arithmetic, subtraction, multiplication, division of today’s calculators. It’s fashioned around something called the Leibniz Wheel, which went on to jumpstart the adding machine industry.”

Silver walked along the wall of glass, pointing out various machines and explaining their historical importance with relish. He asked Tara to walk with him, and as they proceeded he praised her work, asked if she was happy with her position at the company. Despite the short acquaintance, Lash found himself warming to the man: he seemed friendly, free of arrogance.