There were pedestrians and cyclists on the street -- all purely recorded. They were solid rather than ghostly, but it was an eerie kind of solidity; unstoppable, unswayable, they were like infinitely strong, infinitely disinterested robots. Paul hitched a ride on one frail old woman's back for a while; she carried him down the street, heedlessly. Her clothes, her skin, even her hair, all felt the same: hard as steel. Not cold, though. Neutral.

The street wasn't meant to serve as anything but three-dimensional wallpaper; when Copies interacted with each other, they often used cheap, recorded environments full of purely decorative crowds. Plazas, parks, open-air cafes; all very reassuring, no doubt, when you were fighting off a sense of isolation and claustrophobia. Copies could only receive realistic external visitors if they had friends of relatives willing to slow down their mental processes by a factor of seventeen. Most dutiful next-of-kin preferred to exchange video recordings. Who wanted to spend an afternoon with great-grandfather, when it burnt up half a week of your life? Paul had tried calling Elizabeth on the terminal in his study -- which should have granted him access to the outside world, via the computer's communications links -- but, not surprisingly, Durham had sabotaged that as well.

When he reached the corner of the block, the visual illusion of the city continued, far into the distance, but when he tried to step forward onto the road, the concrete pavement under his feet started acting like a treadmill, sliding backward at precisely the rate needed to keep him motionless, whatever pace he adopted. He backed off and tried leaping over the affected region, but his horizontal velocity dissipated -- without the slightest pretense of any "physical" justification -- and he landed squarely in the middle of the treadmill.

The people of the recording, of course, crossed the border with ease. One man walked straight at him; Paul stood his ground -- and found himself pushed into a zone of increasing viscosity, the air around him becoming painfully unyielding, before he slipped free to one side.

The sense that discovering a way to breach this barrier would somehow "liberate" him was compelling -- but he knew it was absurd. Even if he did find a flaw in the program which enabled him to break through, he knew he'd gain nothing but decreasingly realistic surroundings. The recording could only contain complete information for points of view within a certain, finite zone; all there was to "escape to" was a region where his view of the city would be full of distortions and omissions, and would eventually fade to black.

He stepped back from the corner, half dispirited, half amused. What had he hoped to find? A door at the edge of the model, marked exit, through which he could walk out into reality? Stairs leading metaphorically down to some boiler-room representation of the underpinnings of this world, where he could throw a few switches and blow it all apart? He had no right to be dissatisfied with his surroundings; they were precisely what he'd ordered.

What he'd ordered was also a perfect spring day. Paul closed his eyes and turned his face to the sun. In spite of everything, it was hard not to take solace from the warmth flooding onto his skin. He stretched the muscles in his arms, his shoulders, his back -- and it felt like he was reaching out from the "self" in his virtual skull to all his mathematical flesh, imprinting the nebulous data with meaning; binding it all together, staking some kind of claim. He felt the stirrings of an erection. Existence was beginning to seduce him. He let himself surrender for a moment to a visceral sense of identity which drowned out all his pale mental images of optical processors, all his abstract reflections on the software's approximations and short-cuts. This body didn't want to evaporate. This body didn't want to bale out. It didn't much care that there was another -- "more real" -- version of itself elsewhere. It wanted to retain its wholeness. It wanted to endure.

And if this was a travesty of life, there was always the chance of improvement. Maybe he could persuade Durham to restore his communications facilities; that would be a start. And when he grew bored with libraries, news systems, databases, and -- if any of them would deign to meet him -- the ghosts of the senile rich? He could always have himself suspended until processor speeds caught up with reality -- when people would be able to visit without slowdown, and telepresence robots might actually be worth inhabiting.

He opened his eyes, and shivered in the heat. He no longer knew what he wanted -- the chance to bale out, to declare this bad dream over . . . or the possibility of virtual immortality -- but he had to accept that there was only one way he could make the choice his own.

He said quietly, "I won't be your guinea pig. A collaborator, yes. An equal partner. If you want my cooperation, then you're going to have to treat me like a colleague, not a . . . piece of apparatus. Understood?"

A window opened up in front of him. He was shaken by the sight, not of his predictably smug twin, but of the room behind him. It was only his study -- and he'd wandered through the virtual equivalent, unimpressed, just minutes before -- but this was still his first glimpse of the real world, in real time. He moved closer to the window, in the hope of seeing if there was anyone else in the room -- Elizabeth? -- but the image was two-dimensional, the perspective remained unchanged as he approached.

The flesh-and-blood Durham emitted a brief, high-pitched squeak, then waited with visible impatience while a second, smaller window gave Paul a slowed-down replay, four octaves lower:

"Of course that's understood! We're collaborators. That's exactly right. Equals. I wouldn't have it any other way. We both want the same things out of this, don't we? We both need answers to the same questions."

Paul was already having second thoughts. "Perhaps."

But Durham wasn't interested in his qualms.

Squeak. "You know we do! We've waited ten years for this . . . and now it's finally going to happen. And we can begin whenever you're ready."

PART ONE

The Garden-of-Eden Configuration

1

(Remit not paucity)

NOVEMBER 2050

Maria Deluca had ridden past the stinking hole in Pyrmont Bridge Road for six days running, certain each time, as she'd approached, that she'd be greeted by the reassuring sight of a work team putting things right. She knew that there was no money for road works or drainage repairs this year, but a burst sewage main was a serious health risk; she couldn't believe it would be neglected for long.

On the seventh day, the stench was so bad from half a kilometer away that she turned into a side street, determined to find a detour.

This end of Pyrmont was a depressing sight; not every warehouse was empty, not every factory abandoned, but they all displayed the same neglected look, the same peeling paint and crumbling brickwork. Half a dozen blocks west, she turned again -- to be confronted by a vista of lavish gardens, marble statues, fountains and olive groves, stretching into the distance beneath a cloudless azure sky.

Maria accelerated without thinking -- for a few seconds, almost believing that she'd chanced upon a park of some kind, an impossibly well-kept secret in this decaying corner of the city. Then, as the illusion collapsed -- punctured by sheer implausibility as much as any visible flaw -- she pedaled on wilfully, as if hoping to blur the imperfections and contradictions out of existence. She braked just in time, mounting the narrow footpath at the end of the cul-de-sac, the front wheel of her cycle coming to a halt centimeters from the warehouse wall.