Nobody wants to spend eternity alone.

("Intimacy," I once told Sian, after we'd made love, "is the only cure for solipsism." She laughed and said, "Don't get too ambitious, Michael. So far, it hasn't even cured me of masturbation.")

True solipsism, though, was never my problem. From the very first time I considered the question, I accepted that there could be no way of proving the reality of an external world, let alone the existence of other minds - but I also accepted that taking both on faith was the only practical way of dealing with everyday life.

The question which obsessed me was this: Assuming that other people existed, how did they apprehend that existence? How did they experience being? Could I ever truly understand what consciousness was like for another person - any more than I could for an ape, or a cat, or an insect?

If not, I was alone.

I desperately wanted to believe that other people were somehow knowable, but it wasn't something I could bring myself to take for granted. I knew there could be no absolute proof, but I wanted to be persuaded, I needed to be compelled.

No literature, no poetry, no drama, however personally resonant I found it, could ever quite convince me that I'd glimpsed the author's soul. Language had evolved to facilitate cooperation in the conquest of the physical world, not to describe subjective reality. Love, anger, jealousy, resentment, grief - all were defined, ultimately, in terms of external circumstances and observable actions. When an image or metaphor rang true for me, it proved only that I shared with the author a set of definitions, a culturally sanctioned list of word associations. After all, many publishers used computer programs - highly specialised, but unsophisticated algorithms, without the remotest possibility of self-awareness - to routinely produce both literature, and literary criticism, indistinguishable from the human product. Not just formularised garbage, either; on several occasions, I'd been deeply affected by works which I'd later discovered had been cranked out by unthinking software. This didn't prove that human literature communicated nothing of the author's inner life, but it certainly made clear how much room there was for doubt.

Unlike many of my friends, I had no qualms whatsoever when, at the age of eighteen, the time came for me to "switch." My organic brain was removed and discarded, and control of my body handed over to my "jewel" - the Ndoli Device, a neural-net computer implanted shortly after birth, which had since learnt to imitate my brain, down to the level of individual neurons. I had no qualms, not because I was at all convinced that the jewel and the brain experienced consciousness identically, but because, from an early age, I'd identified myself solely with the jewel. My brain was a kind of bootstrap device, nothing more, and to mourn its loss would have been as absurd as mourning my emergence from some primitive stage of embryological neural development. Switching was simply what humans did now, an established part of the life cycle, even if it was mediated by our culture, and not by our genes.

Seeing each other die, and observing the gradual failure of their own bodies, may have helped convince pre-Ndoli humans of their common humanity; certainly, there were countless references in their literature to the equalising power of death. Perhaps concluding that the universe would go on without them produced a shared sense of hopelessness, or insignificance, which they viewed as their defining attribute.

Now that it's become an article of faith that, sometime in the next few billion years, physicists will find a way for us to go on without the universe, rather than vice versa, that route to spiritual equality has lost whatever dubious logic it might ever have possessed.

Sian was a communications engineer. I was a holovision news editor. We met during a live broadcast of the seeding of Venus with terraforming nanomachines - a matter of great public interest, since most of the planet's as-yet-uninhabitable surface had already been sold. There were several technical glitches with the broadcast which might have been disastrous, but together we managed to work around them, and even to hide the seams. It was nothing special, we were simply doing our jobs, but afterwards I was elated out of all proportion. It took me twenty-four hours to realise (or decide) that I'd fallen in love.

However, when I approached her the next day, she made it clear that she felt nothing for me; the chemistry I'd imagined "between us" had all been in my head. I was dismayed, but not surprised. Work didn't bring us together again, but I called her occasionally, and six weeks later my persistence was rewarded. I took her to a performance of Waiting for Godot by augmented parrots, and I enjoyed myself immensely, but I didn't see her again for more than a month.

I'd almost given up hope, when she appeared at my door without warning one night and dragged me along to a "concert" of interactive computerised improvisation. The "audience" was assembled in what looked like a mock-up of a Berlin nightclub of the 2050s. A computer program, originally designed for creating movie scores, was fed with the image from a hover-camera which wandered about the set. People danced and sang, screamed and brawled, and engaged in all kinds of histrionics in the hope of attracting the camera and shaping the music. At first, I felt cowed and inhibited, but Sian gave me no choice but to join in.

It was chaotic, insane, at times even terrifying. One woman stabbed another to "death" at the table beside us, which struck me as a sickening (and expensive) indulgence, but when a riot broke out at the end, and people started smashing the deliberately flimsy furniture, I followed Sian into the melee, cheering.

The music - the excuse for the whole event - was garbage, but I didn't really care. When we limped out into the night, bruised and aching and laughing, I knew that at least we'd shared something that had made us feel closer. She took me home and we went to bed together, too sore and tired to do more than sleep, but when we made love in the morning I already felt so at ease with her that I could hardly believe it was our first time.

Soon we were inseparable. My tastes in entertainment were very different from hers, but I survived most of her favourite "artforms", more or less intact. She moved into my apartment, at my suggestion, and casually destroyed the orderly rhythms of my carefully arranged domestic life.

I had to piece together details of her past from throwaway lines; she found it far too boring to sit down and give me a coherent account. Her life had been as unremarkable as mine: she'd grown up in a suburban, middle-class family, studied her profession, found a job. Like almost everyone, she'd switched at eighteen. She had no strong political convictions. She was good at her work, but put ten times more energy into her social life. She was intelligent, but hated anything overtly intellectual. She was impatient, aggressive, roughly affectionate.

And I could not, for one second, imagine what it was like inside her head.

For a start, I rarely had any idea what she was thinking - in the sense of knowing how she would have replied if asked, out of the blue, to describe her thoughts at the moment before they were interrupted by the question. On a longer time scale, I had no feeling for her motivation, her image of herself, her concept of who she was and what she did and why. Even in the laughably crude sense that a novelist pretends to "explain" a character, I could not have explained Sian.

And if she'd provided me with a running commentary on her mental state, and a weekly assessment of the reasons for her actions in the latest psychodynamic jargon, it would all have come to nothing but a heap of useless words. If I could have pictured myself in her circumstances, imagined myself with her beliefs and obsessions, empathised until I could anticipate her every word, her every decision, then I still would not have understood so much as a single moment when she closed her eyes, forgot her past, wanted nothing, and simply was.

Of course, most of the time, nothing could have mattered less. We were happy enough together, whether or not we were strangers - and whether or not my "happiness" and Sian's "happiness" were in any real sense the same.

Over the years, she became less self-contained, more open. She had no great dark secrets to share, no traumatic childhood ordeals to recount, but she let me in on her petty fears and her mundane neuroses. I did the same, and even, clumsily, explained my peculiar obsession. She wasn't at all offended. Just puzzled.

"What could it actually mean, though? To know what it's like to be someone else? You'd have to have their memories, their personality, their body - everything. And then you'd just be them, not yourself, and you wouldn't know anything. It's nonsense."

I shrugged. "Not necessarily. Of course, perfect knowledge would be impossible, but you can always get closer. Don't you think that the more things we do together, the more experiences we share, the closer we become?"

She scowled. "Yes, but that's not what you were talking about five seconds ago. Two years, or two thousand years, of 'shared experiences' seen through different eyes means nothing. However much time two people spent together, how could you know that there was even the briefest instant when they both experienced what they were going through 'together' in the same way?"

"I know, but . . ."

"If you admit that what you want is impossible, maybe you'll stop fretting about it."

I laughed. "Whatever makes you think I'm as rational as that?"

When the technology became available it was Sian's idea, not mine, for us to try out all the fashionable somatic permutations. Sian was always impatient to experience something new. "If we really are going to live forever," she said, "we'd better stay curious if we want to stay sane."

I was reluctant, but any resistance I put up seemed hypocritical. Clearly, this game wouldn't lead to the perfect knowledge I longed for (and knew I would never achieve), but I couldn't deny the possibility that it might be one crude step in the right direction.

First, we exchanged bodies. I discovered what it was like to have breasts and a vagina - what it was like for me, that is, not what it had been like for Sian. True, we stayed swapped long enough for the shock, and even the novelty, to wear off, but I never felt that I'd gained much insight into her experience of the body she'd been born with. My jewel was modified only as much as was necessary to allow me to control this unfamiliar machine, which was scarcely more than would have been required to work another male body. The menstrual cycle had been abandoned decades before, and although I could have taken the necessary hormones to allow myself to have periods, and even to become pregnant (although the financial disincentives for reproduction had been drastically increased in recent years), that would have told me absolutely nothing about Sian, who had done neither.

As for sex, the pleasure of intercourse still felt very much the same - which was hardly surprising, since nerves from the vagina and clitoris were simply wired into my jewel as if they'd come from my penis. Even being penetrated made less difference than I'd expected; unless I made a special effort to remain aware of our respective geometries, I found it hard to care who was doing what to whom. Orgasms were better though, I had to admit.

At work, no one raised an eyebrow when I turned up as Sian, since many of my colleagues had already been through exactly the same thing. The legal definition of identity had recently been shifted from the DNA fingerprint of the body, according to a standard set of markers, to the serial number of the jewel. When even the law can keep up with you, you know you can't be doing anything very radical or profound.

After three months, Sian had had enough. "I never realised how clumsy you were," she said. "Or that ejaculation was so dull."

Next, she had a clone of herself made, so we could both be women. Brain-damaged replacement bodies - Extras - had once been incredibly expensive, when they'd needed to be grown at virtually the normal rate, and kept constantly active so they'd be healthy enough to use. However, the physiological effects of the passage of time, and of exercise, don't happen by magic; at a deep enough level, there's always a biochemical signal produced, which can ultimately be faked. Mature Extras, with sturdy bones and perfect muscle tone, could now be produced from scratch in a year - four months' gestation and eight months' coma - which also allowed them to be more thoroughly brain-dead than before, soothing the ethical qualms of those who'd always wondered just how much was going on inside the heads of the old, active versions.

In our first experiment, the hardest part for me had always been, not looking in the mirror and seeing Sian, but looking at Sian and seeing myself. I'd missed her, far more than I'd missed being myself. Now, I was almost happy for my body to be absent (in storage, kept alive by a jewel based on the minimal brain of an Extra). The symmetry of being her twin appealed to me; surely now we were closer than ever. Before, we'd merely swapped our physical differences. Now, we'd abolished them.

The symmetry was an illusion. I'd changed gender, and she hadn't. I was with the woman I loved; she lived with a walking parody of herself.

One morning she woke me, pummelling my breasts so hard that she left bruises. When I opened my eyes and shielded myself, she peered at me suspiciously. "Are you in there? Michael? I'm going crazy. I want you back."

For the sake of getting the whole bizarre episode over and done with for good - and perhaps also to discover for myself what Sian had just been through - I agreed to the third permutation. There was no need to wait a year; my Extra had been grown at the same time as hers.

Somehow, it was far more disorienting to be confronted by "myself" without the camouflage of Sian's body. I found my own face unreadable; when we'd both been in disguise, that hadn't bothered me, but now it made me feel edgy, and at times almost paranoid, for no rational reason at all.

Sex took some getting used to. Eventually, I found it pleasurable, in a confusing and vaguely narcissistic way. The compelling sense of equality I'd felt, when we'd made love as women, never quite returned to me as we sucked each other's cocks - but then, when we'd both been women, Sian had never claimed to feel any such thing. It had all been my own invention.

The day after we returned to the way we'd begun (well, almost - in fact, we put our decrepit, twenty-six-year-old bodies in storage, and took up residence in our healthier Extras), I saw a story from Europe on an option we hadn't yet tried, tipped to become all the rage: hermaphroditic identical twins. Our new bodies could be our biological children (give or take the genetic tinkering required to ensure hermaphroditism), with an equal share of characteristics from both of us. We would both have changed gender, both have lost partners. We'd be equal in every way.

I took a copy of the file home to Sian. She watched it thoughtfully, then said, "Slugs are hermaphrodites, aren't they? They hang in mid-air together on a thread of slime. I'm sure there's even something in Shakespeare, remarking on the glorious spectacle of copulating slugs. Imagine it: you and me, making slug love."

I fell on the floor, laughing.

I stopped, suddenly. "Where, in Shakespeare? I didn't think you'd even read Shakespeare."

Eventually, I came to believe that with each passing year, I knew Sian a little better - in the traditional sense, the sense that most couples seemed to find sufficient. I knew what she expected from me, I knew how not to hurt her. We had arguments, we had fights, but there must have been some kind of underlying stability, because in the end we always chose to stay together. Her happiness mattered to me, very much, and at times I could hardly believe that I'd ever thought it possible that all of her subjective experience might be fundamentally alien to me. It was true that every brain, and hence every jewel, was unique - but there was something extravagant in supposing that the nature of consciousness could be radically different between individuals, when the same basic hardware, and the same basic principles of neural topology, were involved.

Still. Sometimes, if I woke in the night, I'd turn to her and whisper, inaudibly, compulsively, "I don't know you. I have no idea who, or what, you are." I'd lie there, and think about packing and leaving. I was alone, and it was farcical to go through the charade of pretending otherwise.

Then again, sometimes I woke in the night, absolutely convinced that I was dying, or something else equally absurd. In the sway of some half-forgotten dream, all manner of confusion is possible. It never meant a thing, and by morning I was always myself again.

When I saw the story on Craig Bentley's service - he called it "research," but his "volunteers" paid for the privilege of taking part in his experiments - I almost couldn't bring myself to include it in the bulletin, although all my professional judgement told me it was everything our viewers wanted in a thirty second techno-shock piece: bizarre, even mildly disconcerting, but not too hard to grasp.

Bentley was a cyberneurologist; he studied the Ndoli Device, in the way that neurologists had once studied the brain. Mimicking the brain with a neural-net computer had not required a profound understanding of its higher-level structures; research into these structures continued, in their new incarnation. The jewel, compared to the brain, was of course both easier to observe, and easier to manipulate.

In his latest project, Bentley was offering couples something slightly more up-market than an insight into the sex lives of slugs. He was offering them eight hours with identical minds.

I made a copy of the original, ten-minute piece that had come through on the fibre, then let my editing console select the most titillating thirty seconds possible, for broadcast. It did a good job; it had learnt from me.

I couldn't lie to Sian. I couldn't hide the story, I couldn't pretend to be disinterested. The only honest thing to do was to show her the file, tell her exactly how I felt, and ask her what she wanted.

I did just that. When the HV image faded out, she turned to me, shrugged, and said mildly, "Okay. It sounds like fun. Let's try it."

Bentley wore a T-shirt with nine computer-drawn portraits on it, in a three-by-three grid. Top left was Elvis Presley. Bottom right was Marilyn Monroe. The rest were various stages in between.

"This is how it will work. The transition will take twenty minutes, during which time you'll be disembodied. Over the first ten minutes, you'll gain equal access to each other's memories. Over the second ten minutes, you'll both be moved, gradually, towards the compromise personality.

"Once that's done, your Ndoli Devices will be identical - in the sense that both will have all the same neural connections with all the same weighting factors - but they'll almost certainly be in different states. I'll have to black you out, to correct that. Then you'll wake - "

Who'll wake?

" - in identical electromechanical bodies. Clones can't be made sufficiently alike.

"You'll spend the eight hours alone, in perfectly matched rooms. Rather like hotel suites, really. You'll have HV to keep you amused if you need it - without the videophone module, of course. You might think you'd both get an engaged signal, if you tried to call the same number simultaneously - but in fact, in such cases the switching equipment arbitrarily lets one call through, which would make your environments different."

Sian asked, "Why can't we phone each other? Or better still, meet each other? If we're exactly the same, we'd say the same things, do the same things - we'd be one more identical part of each other's environment."

Bentley pursed his lips and shook his head. "Perhaps I'll allow something of the kind in a future experiment, but for now I believe it would be too . . . potentially traumatic."

Sian gave me a sideways glance, which meant: This man is a killjoy.

"The end will be like the beginning, in reverse. First, your personalities will be restored. Then, you'll lose access to each other's memories. Of course, your memories of the experience itself will be left untouched. Untouched by me, that is; I can't predict how your separate personalities, once restored, will act - filtering, suppressing, reinterpreting those memories. Within minutes, you may end up with very different ideas about what you've been through. All I can guarantee is this: For the eight hours in question, the two of you will be identical."

We talked it over. Sian was enthusiastic, as always. She didn't much care what it would be like; all that really mattered to her was collecting one more novel experience.

"Whatever happens, we'll be ourselves again at the end of it," she said. "What's there to be afraid of? You know the old Ndoli joke."

"What old Ndoli joke?"

"Anything's bearable - so long as it's finite."

I couldn't decide how I felt. The sharing of memories notwithstanding, we'd both end up knowing, not each other, but merely a transient, artificial third person. Still, for the first time in our lives, we would have been through exactly the same experience, from exactly the same point of view - even if the experience was only spending eight hours locked in separate rooms, and the point of view was that of a genderless robot with an identity crisis.

It was a compromise - but I could think of no realistic way in which it could have been improved.

I called Bentley, and made a reservation.

In perfect sensory deprivation, my thoughts seemed to dissipate into the blackness around me before they were even half-formed. This isolation didn't last long, though; as our short-term memories merged, we achieved a kind of telepathy: One of us would think a message, and the other would "remember" thinking it, and reply in the same way.

- I really can't wait to uncover all your grubby little secrets.

- I think you're going to be disappointed. Anything I haven't already told you, I've probably repressed.

- Ah, but repressed is not erased. Who knows what will turn up?

- We'll know, soon enough.

I tried to think of all the minor sins I must have committed over the years, all the shameful, selfish, unworthy thoughts, but nothing came into my head but a vague white noise of guilt. I tried again, and achieved, of all things, an image of Sian as a child. A young boy slipping his hand between her legs, then squealing with fright and pulling away. But she'd described that incident to me, long ago. Was it her memory, or my reconstruction?

- My memory. I think. Or perhaps my reconstruction. You know, half the time when I've told you something that happened before we met, the memory of the telling has become far clearer to me than the memory itself. Almost replacing it.

- It's the same for me.

- Then in a way, our memories have already been moving towards a kind of symmetry, for years. We both remember what was said, as if we'd both heard it from someone else.

Agreement. Silence. A moment of confusion. Then:

- This neat division of "memory" and "personality" Bentley uses; is it really so clear? Jewels are neural-net computers; you can't talk about "data" and "program" in any absolute sense.

- Not in general, no. His classification must be arbitrary, to some extent. But who cares?

- It matters. If he restores "personality," but allows "memories" to persist, a misclassification could leave us . . .

- What?

- It depends, doesn't it? At one extreme, so thoroughly "restored," so completely unaffected, that the whole experience might as well not have happened. And at the other extreme . . .

- Permanently . . .

- . . . closer.

- Isn't that the point?

- I don't know anymore.

Silence. Hesitation.

Then I realised that I had no idea whether or not it was my turn to reply.

I woke, lying on a bed, mildly bemused, as if waiting for a mental hiatus to pass. My body felt slightly awkward, but less so than when I'd woken in someone else's Extra. I glanced down at the pale, smooth plastic of my torso and legs, then waved a hand in front of my face. I looked like a unisex shop-window dummy - but Bentley had shown us the bodies beforehand, it was no great shock. I sat up slowly, then stood and took a few steps. I felt a little numb and hollow, but my kinaesthetic sense, my proprioception, was fine; I felt located between my eyes, and I felt that this body was mine. As with any modern transplant, my jewel had been manipulated directly to accommodate the change, avoiding the need for months of physiotherapy.

I glanced around the room. It was sparsely furnished: one bed, one table, one chair, one clock, one HV set. On the wall, a framed reproduction of an Escher lithograph: "Bond of Union," a portrait of the artist and, presumably, his wife, faces peeled like lemons into helices of rind, joined into a single, linked band. I traced the outer surface from start to finish, and was disappointed to find that it lacked the Möbius twist I was expecting.

No windows, one door without a handle. Set into the wall beside the bed, a full-length mirror. I stood a while and stared at my ridiculous form. It suddenly occurred to me that, if Bentley had a real love of symmetry games, he might have built one room as the mirror image of the other, modified the HV set accordingly, and altered one jewel, one copy of me, to exchange right for left. What looked like a mirror could then be nothing but a window between the rooms. I grinned awkwardly with my plastic face; my reflection looked appropriately embarrassed by the sight. The idea appealed to me, however unlikely it was. Nothing short of an experiment in nuclear physics could reveal the difference. No, not true; a pendulum free to precess, like Foucault's, would twist the same way in both rooms, giving the game away. I walked up to the mirror and thumped it. It didn't seem to yield at all, but then, either a brick wall, or an equal and opposite thump from behind, could have been the explanation.

I shrugged and turned away. Bentley might have done anything - for all I knew, the whole set-up could have been a computer simulation. My body was irrelevant. The room was irrelevant. The point was . . .

I sat on the bed. I recalled someone - Michael, probably - wondering if I'd panic when I dwelt upon my nature, but I found no reason to do so. If I'd woken in this room with no recent memories, and tried to sort out who I was from my past(s), I'd no doubt have gone mad, but I knew exactly who I was, I had two long trails of anticipation leading to my present state. The prospect of being changed back into Sian or Michael didn't bother me at all; the wishes of both to regain their separate identities endured in me, strongly, and the desire for personal integrity manifested itself as relief at the thought of their re-emergence, not as fear of my own demise. In any case, my memories would not be expunged, and I had no sense of having goals which one or the other of them would not pursue. I felt more like their lowest common denominator than any kind of synergistic hypermind; I was less, not more, than the sum of my parts. My purpose was strictly limited: I was here to enjoy the strangeness for Sian, and to answer a question for Michael, and when the time came I'd be happy to bifurcate, and resume the two lives I remembered and valued.

So, how did I experience consciousness? The same way as Michael? The same way as Sian? So far as I could tell, I'd undergone no fundamental change - but even as I reached that conclusion, I began to wonder if I was in any position to judge. Did memories of being Michael, and memories of being Sian, contain so much more than the two of them could have put into words and exchanged verbally? Did I really know anything about the nature of their existence, or was my head just full of second-hand description - intimate, and detailed, but ultimately as opaque as language? If my mind were radically different, would that difference be something I could even perceive - or would all my memories, in the act of remembering, simply be recast into terms that seemed familiar?

The past, after all, was no more knowable than the external world. Its very existence also had to be taken on faith - and, granted existence, it too could be misleading.

I buried my head in my hands, dejected. I was the closest they could get, and what had come of me? Michael's hope remained precisely as reasonable - and as unproven - as ever.

After a while, my mood began to lighten. At least Michael's search was over, even if it had ended in failure. Now he'd have no choice but to accept that, and move on.

I paced around the room for a while, flicking the HV on and off. I was actually starting to get bored, but I wasn't going to waste eight hours and several thousand dollars by sitting down and watching soap operas.

I mused about possible ways of undermining the synchronisation of my two copies. It was inconceivable that Bentley could have matched the rooms and bodies to such a fine tolerance that an engineer worthy of the name couldn't find some way of breaking the symmetry. Even a coin toss might have done it, but I didn't have a coin. Throwing a paper plane? That sounded promising - highly sensitive to air currents - but the only paper in the room was the Escher, and I couldn't bring myself to vandalise it. I might have smashed the mirror, and observed the shapes and sizes of the fragments, which would have had the added bonus of proving or disproving my earlier speculations, but as I raised the chair over my head, I suddenly changed my mind. Two conflicting sets of short-term memories had been confusing enough during a few minutes of sensory deprivation; for several hours interacting with a physical environment, it could be completely disabling. Better to hold off until I was desperate for amusement.

So I lay down on the bed and did what most of Bentley's clients probably ended up doing.

As they coalesced, Sian and Michael had both had fears for their privacy - and both had issued compensatory, not to say defensive, mental declarations of frankness, not wanting the other to think that they had something to hide. Their curiosity, too, had been ambivalent; they'd wanted to understand each other, but, of course, not to pry.

All of these contradictions continued in me, but - staring at the ceiling, trying not to look at the clock again for at least another thirty seconds - I didn't really have to make a decision. It was the most natural thing in the world to let my mind wander back over the course of their relationship, from both points of view.

It was a very peculiar reminiscence. Almost everything seemed at once vaguely surprising and utterly familiar - like an extended attack of deja vu. It's not that they'd often set out deliberately to deceive each other about anything substantial, but all the tiny white lies, all the concealed trivial resentments, all the necessary, laudable, essential, loving deceptions, that had kept them together in spite of their differences, filled my head with a strange haze of confusion and disillusionment.

It wasn't in any sense a conversation; I was no multiple personality. Sian and Michael simply weren't there - to justify, to explain, to deceive each other all over again, with the best intentions. Perhaps I should have attempted to do all this on their behalf, but I was constantly unsure of my role, unable to decide on a position. So I lay there, paralysed by symmetry, and let their memories flow.

After that, the time passed so quickly that I never had a chance to break the mirror.

We tried to stay together.

We lasted a week.

Bentley had made - as the law required - snapshots of our jewels prior to the experiment. We could have gone back to them - and then had him explain to us why - but self-deception is only an easy choice if you make it in time.

We couldn't forgive each other, because there was nothing to forgive. Neither of us had done a single thing that the other could fail to understand, and sympathise with, completely.

We knew each other too well, that's all. Detail after tiny fucking microscopic detail. It wasn't that the truth hurt; it didn't, any longer. It numbed us. It smothered us. We didn't know each other as we knew ourselves; it was worse than that. In the self, the details blur in the very processes of thought; mental self-dissection is possible, but it takes great effort to sustain. Our mutual dissection took no effort at all; it was the natural state into which we fell in each other's presence. Our surfaces had been stripped away, but not to reveal a glimpse of the soul. All we could see beneath the skin were the cogs, spinning.

And I knew, now, that what Sian had always wanted most in a lover was the alien, the unknowable, the mysterious, the opaque. The whole point, for her, of being with someone else was the sense of confronting otherness. Without it, she believed, you might as well be talking to yourself.

I found that I now shared this view (a change whose precise origins I didn't much want to think about . . . but then, I'd always known she had the stronger personality, I should have guessed that something would rub off).

Together, we might as well have been alone, so we had no choice but to part.

Nobody wants to spend eternity alone.

Greg's first novel Quarantine is due in September from Century Legend.

Originally appeared in Eidolon 8,April 1992.
Copyright © 1991 Greg Egan. All rights reserved.

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