First, this inky vault through which he flew. Windless, without warmth or the rub of the real.

 He delved down into the working mathematics of himself. It was a byzantine welter of detail, but in outline surprisingly familiar: the Cartesian world. Events were modeled with axes in rectangular space, x, y, z, so that motion was then merely sets of numbers on each axis. All dynamics shrank to arithmetic. Descartes would have been amused by the dizzying heights to which his minor method had spun.

 He rejected the outside and delved into his own slowed reaches.

 Now he couldfeel his preconscious reading the incoming sights, sounds, and flitting thoughts of the moment. To his inner gaze, they all carried bright red tags—sometimes simple caricatures, often complex packets.

 From somewhere an idea-packet arrived, educating him: these were Fourier transforms. Somehow this helped to understand. And the mere wafting sense of a fellow Frenchman’s name made him feel better.

 An Associator—big, blue, bulbous—hovered over this data-field, plucking at the tags. It reached with yellow streamers over a far, purple-rimmed horizon, to the Field of Memory. From there it brought any item stored—packages of mottled gray, containing sights, sounds, smells, ideas—which matched the incoming tags.

 Job done, the Associator handed all the matchings to a towering monolith: the Discriminator. A perpetual wind sucked the red tags up, into the yawning surfaces of the coal-black Discriminator mountain. Merciless filters there matched the tags with the stored memories.

 If they fitted—geometric shapes sliding together, mock sex, notches fitting snugly into protruding struts—they stayed. But fits were few. Most tags failed to find a host memory which made sense. No fit. These the Discriminator ate. The tags and connections vanished, swept away to clear fresh space for the next flood of sensation.

 He loomed over this interior landscape and felt its hailstorm power. His whole creative life, the marvel of continents, had come from here. Tiny thoughts, snatches of conversations, melodies—all would pop into his mind, a tornado of chaos-images, crowding, jostling for his attention. The memory-packets which shared some sturdy link to a tag endured.

 But who decided what was rugged enough? He watched rods slide into slots and saw the intricate details of how those memories and tags were shaped. So the answer lay at least one step further back, in the geometry of memory.

 Which meant that he had determined matters, by the laying down of memories. Memory-clumps, married to tag-streams, made a portion of his Self, plucked forth from the torrent, the river of possibilities.

 And he had done it long ago, when the memories were stored—all without realizing how they could fit with tags to come. So where was any predictable Voltaire to lurk? In sheer intricacy, deep detail, shifting associations in the flow.

 No rock-hard Self at all.

 And his imagination? The author of all his plays and essays? It must lie in the weather of the tag-memory torrents. The twist, warp and sudden marriages. Jigsaw associations, rising up from the preconscious. Order from chaos.

 “Who is Voltaire?” he called to the streaming gridded emptiness.

 No reply.

 His itch was still with him. And the yawning nothing all around. He decided to fix the larger issue. What had Pascal said?

 The silence of these spaces terrifies me.

 He probed and gouged and sought. And in the doing, knew that as his hands dug into the ebony stuff all about him, they were but metaphors. Symbols for programs he could never have created himself.

 He had inherited these abilities—much as he had, as a boy, in­ herited hands. Down below his conscious Self, his minions had labored upon the base Volt 1.0, plus Marq’s augmentations.

 He pulled apart the blackness and stepped through. To a city street.

 He was puffing, weak, strained. Resources running low.

 He walked shakily into a restaurant—anonymous, plain, food merely standing on counters—and stuffed himself.

 He concentrated on each step. By making each portion of his experience well up, he found that he could descend through the layers of his own response.

 Making his body feel right demanded sets of overlapping rules. As he chewed, teeth had to sink into food, saliva squirt to greet the munched mass, enzymes start to work to extract the right nutrient ratios—else it would not seem real.

 His programs, he saw, bypassed the involved stomach and colon processes. Such intricacies were needless. Instead, the “software” (odd phrase) simplified all the messy innards into a result he could feel—a satisfying con­ centration of tasty blood sugars, giving him a carbohydrate lift, a pleasant electrolyte balance, hormones and stabilizers all calculated, with a patchwork of templates for the appropriate emotional levels.

 All other detail was discarded, once the subroutines got the right effect, simulating the tingling of nerve endings. Not too bad for what was really a block of ferrite and polymer, each site in its crystal complexity an individual, furiously working microprocessor.

 Still, he felt as though he had been hollowed out by an intense, sucking vacuum.

 Voltaire rushed out of the restaurant. The street! He needed to see this place, to check his suspicions.

 Down the placid avenues he lurched. Run, stride!

 Even though reckless, he never accidentally fell. Inspection of his inner layers showed that this was because his peripheral vision ex­ tended beyond 180 degrees, taking everything in. So he was literally seeing behind his head—though he did not consciously register this.

 Real people, he suddenly saw, negotiated steps while chattering to each other by making snapshot comparisons of their peripheral vision; they were acutely sensitive to sudden changes in silhouettes and trajectories. Balance and walking were so critical to humans that his programming overdid its caution.

 He had to teeter far out on his toes before he could fall on his face—smack!—and even then it didn’t hurt much.

 Once there, he let a passerby walk over him. A girl—a nominal girl, the phrase leapt to mind—stepped on him.

 This time he cringed at the downward spike of her heels…and felt nothing. He scrambled after her. Some elementary portion of himself had feared the pain.

 So it had eliminated it. Which meant that experience was no longer a constraint.

 “The spirit has won a divorce from the body!” he announced to the people passing by. Stolid, they paid him no heed.

 But this was his simulation!

 Outraged, he caught up to the methodical girl and jumped powerfully onto her shoulders. No effect. He rode her down the street. The girl strode on obliviously as he danced on her head. The apparently fragile sim-girl was a recorded patch-in, as solid and remorseless as rock.

 He danced down the street by leaping from head to head. Nobody noticed; every head felt firm, a smoothly gliding platform.

 So the entire street was backdrop, no better than it had to be. The crowd did not repeat as a whole, but three times he saw the same elderly woman making her crabbed way on the slidewalk, on the exact same route, with the identical shopping bag.

 It was eerie, watching people passing by and knowing that they were as unreachable as a distant star. No, even less; the Empire had stars aplenty.

 And how did he know that?

 Voltaire felt knowledge unfold in him like a dense matting, a cloak wrapping him.

 Suddenly, he itched. Not a mere vexation, but a wave of terrible tingling that swept in waves over his entire body. Indeed, inside his body.

 He ran down the street, swatting at himself. The physical gesture should stimulate his subselves, make them solve this problem. It did not.

 Prickly pain sheeted over his skin. It danced like St. Elmo’s fire, a natural phenomenon akin to ball lightning—or so a subself blithely informed him, as if he desired—

 “Library learning!” he shouted. “Not that! I want—”

 Your fine astronomers can find the distance of the stars, and their temperatures and metal content. But how do they find out what their true names are?

 The voice spoke without sound. It reverberated not in his ears but in mind. He felt cold fear at the blank strangeness of the flat, humorless tone. It chilled him.

 “Who jokes?”

 No answer.

 “Who, damn you?” Joan had termed the blankness an It.

 He hurried on, but felt eyes everywhere.

 6.

 He had an interest in politics, the game of so many second-rates. Should he tarry, learning of Trantor’s troubles? No; necessity beckoned.

 He had to maintain himself. This meant doing his chores, as his wizened mother had once termed it. If only the crone could see him now, doing unimaginable tasks in a labyrinth beyond concep­ tion.

 Abruptly he felt a spike of remembrance—pain, a sharp nostalgia for a time and place he knew was no more than dust blowing in winds…all on some world these people had lost. Earth itself, gone! How could they let such a travesty occur?

 Voltaire simmered with frustrated anger and got to work. Throughout his life, as he had scribbled his plays and amassed a fortune, he had always taken refuge in his labors.

 To run his background—that was his job. Strange phrase.

 Somewhere within him, an agent ferreted out the expert programs which understood how to create his exterior frame. He had to do it, though, sweat breaking out upon his linen, muscles straining against—what? He could see nothing.

 He split the tasks. Part of him knew what truly happened, though the core-Voltaire felt only manual labor.

 His smart Self felt the process in detail. Pickpocketing running time on machine bases, he got computations done on the sly. The trick could only work until the next round of program-checking, when his minor theft would be detected—then sniffed out and deftly traced, with punishment following close on the bloodhounds’ heels.

 To avoid this, he spread himself into N platforms, scattered within Trantor, with N a number typically greater than ten thou­ sand. When the small slivers of the sim felt a watchdog approach­ ing, they could escape the platform in question. A task-agent ex­ plained that this was at a rate inversely proportional to the running space they had captured—though this explanation was quite opaque to the core-Self.

 Small pieces escaped faster. So for security, he divided the entire sim, including himself (and Joan, an agent reminded him—they were connected, through tiny roots) into ever finer slices. These ran on myriad platforms, wherever space became available.

 Slowly, his externals congealed about him.

 He could make a tree limb blow in the breeze, articulating gently…all thanks to a few giga-slots of space left open during a momentary handshake protocol, as gargantuan accounting programs shifted, on a Bank Exchange layer.

 Stitching back together the whole Self, all from the sum of slivers, was itself a job he farmed out to microservers. He imagined himself as a man made like a mountain of ants. From a distance, perhaps convincing. Up close, one had to wonder.

 But the one doing the wondering was the ant mountain itself.

 His own visceral sense of Self—was that rock-solid, too, just a patched-in slug of digits? Or a mosaic of ten thousand ad hoc rules, running together? Was either answer better than the other?

 He was taking a walk. Most pleasant.

 This town, he had learned, was only a few streets and a backdrop. As he sauntered down an avenue, details started to smooth out, and finally he could step no further into the air, now molasses-thick. He could go no further.

 He turned and regarded the apparently ordinary world. How was this done?

 His eyes were simulated in great detail, down to individual cells, rods, and cones responding differently to light. A program traced light rays from his retina to the outside “world,” lines running op­ posite to the real world, to calculate what he could see. Like the eye itself, it computed fine details at the center of vision, shading off to rougher patches at the edge. Objects out of sight could still cast glows or shadows into the field of vision, so had to be kept crudely in the program. Once he looked away, the delicate dew­ drops on a lush rose would collapse into a crude block of opaque backdrop.

 Knowing this, he tried to snap his head back around and catch the program off guard, glimpse a gray world of clumsy form-fitting squares and blobs—and always failed. Vision fluttered at twenty-two frames per second at best; the sim could retrace itself with ease in that wide a wedge of time.

 “Ah, Newton!” Voltaire shouted to the oblivious crowds who paced endlessly through their tissue-thin streets. “You knew optics, but now I—merely by asking myself a question—can fathom light more deeply than thee!”