'Oh, that,' I said. 'Well apart from all the usual personal stuff I want to be a humanist philosopher.'

I fully expected Sophie to laugh in my face. A humanist? Philosopher? You?

She looked puzzled. 'Why humanist? I mean, isn't that a bit wishy-washy? Like a sort of none-of-the-above thing?'

'No ... well, yes, it is a bit. But it doesn't have to be. Think what we could be like if we took our real situation seriously.'

'This is the only life we have, and all that?'

'Yes, that, sure,' I said, 'but more important I think is to take seriously that we're just at the beginning of history, that humanity might well have millions of years still to come. We've just about got over the idea from the Bible that we've only had a short past, a few thousand years, right?'

'Half the Americans haven't got over it,' Sophie pointed out. 'Plus there are lots of Muslims who seem to be taking it up.'

'Tell me about it,' I said, laughing. 'Look at this.'

I swung my rucksack onto my lap and hauled out a small stack of books and pamphlets, which I flicked through to show Sophie how I used them: a battered, black-bound, copy of the Authorized Version of the Bible, with verses I'd highlighted and annotated in four different colours of ink to cross-reference contradictions, unfulfilled prophecies, absurdities, and atrocities; Marmaduke Pickthall's translation of the Koran, in which I'd been careful to mark pages only with variously coloured tabs; a paperback Origin of Species, with the passages marked that were most often truncated in creationist quote-mangling; several copies each of booklets from the Royal Society and the National Academy of Sciences, explaining evolution and the age of the Earth in the simplest possible terms for the benefit of creationists; The Counter-Creationism Handbook, conveniently indexing and debunking creationist claims; and a few other books and pamphlets doing the same for alternative medicine and UFOs.

'I've got lots of similar stuff on memory sticks too,' I added, reaching to the bottom of my bag and fishing out a fistful. 'Quite often when I'm arguing with Christian Union or Islamic Society types they'll take a memory stick when they won't take a pamphlet.'

Sophie looked at me somewhat askance. 'You do a lot of this?'

'Well ... I stop by the stall on my way to lunch, sometimes. Or when these people turn up at Humanist events, it's always good to have refutations handy.'

'Seems a bit of an ... odd hobby.'

'Maybe it is,' I said. 'Anyway, it isn't my main thing. Like I was saying, my point is that even people who've got over the idea of a short past are still stuck in the idea of a short future, which also comes from Christianity a from the opposite end of the Bible, in fact, from Revelation. That we're living in the End Times. We just have secular versions of it, like global-warming catastrophe or nuclear war or the final crisis of capitalism all being imminent in this century.'

Sophie smiled. 'Some might say there are good reasons to think any or all of them are.'

'Yes, but-'

She raised a hand. 'Wait. I think I need a coffee.'

'I'll ...' I half rose.

'No, I'll,' she said, waving a card. 'You?'

'Black, no sugar.'

'OK. Mind my bag.'

While she waited at the bar I looked her up on my phone. She had an open-ended CV on a network that consisted of everyone else doing the same a brusque and business-like; a photo album of dress-design sketches, family and landscape pics, with the odd close-up of architectural detail; and the usual Splatter trail of thousands of cryptic remarks. I wasn't surprised: like me and most of the more thoughtful of our cohort, she'd evidently acquired from older, sadder and wiser relatives an early wariness about online self-exposure. Were she and Calum still a couple? I didn't know, and her online footprint showed no traces either way. I could have asked her, but it would have felt awkward.

Something buzzed past my ear as I put away my phone. My head jerked reflexively and I saw a camcopter the size of a bee, hovering above the next table for a second or two, then darting away above the bar and zooming out of the open door to the patio. I saw an arm swipe above a head, heard a laugh. Usually the little buggers moved too fast to see properly, let alone to swat. In the glass tower of Informatics, no doubt, some engineering student was having a laugh.

Sophie returned, balancing cups on saucers. She sat down with them still in her hands, in a smooth movement that vaguely disturbed me because I found it sexy and because it reminded me of the actions of the mysterious minister.

'You were saying. Millions of years?'

'Billions,' I said. 'In fact, it's more than that. Trillions. Look. We all know there's a deep past, right? But we're still thinking about it in the wrong way. Stephen J. Gould or somebody' a I resisted the impulse to look it up a 'came up with a nice image for the past. Do you ever smooth your nails?'

She waggled her fingers and gave me a look.

'OK. If you were to stand on tiptoe or' a I glanced at her boots a 'in high heels, say, and stretch up your arm as high as you could above your head, and we take that as representing the age of the Earth, then you sit down, I guess, and take the end of the nail of your middle finger and give it one swipe across with the, uh ...'

'Emery board?'

'Yes. Then you've just wiped out what on that scale is the whole of human history.'

'Cool,' Sophie said, leaning forward and blowing on her coffee. 'Sort of puts things in perspective.'

'That's the idea, yes,' I said. 'Or there's the other example with the whole four and a half billion years represented by a twenty-four-hour clock, and our history is all in the last second or the last tick or whatever. But that's all wrong. I mean, it's right as far as it goes, but what people usually take from it is like "Oh, we're so insignificant!", because they forget what it leaves out.'

'Ah!' Sophie said. 'Yes! It leaves out the scale of the changes we've made.'

I was momentarily thrown. I hadn't thought of that.

'That's a very good point,' I said. 'But it wasn't the one I was thinking of. What the tippy-toes and the clock things leave out is the future. All the ages to come, in the immense future of the universe. That's the real deep time, and on that scale four point five billion years is a very small thing.'

Sophie laughed. 'So we're even more insignificant!'

'No, no,' I said. 'Don't you see? We're just at the beginning of things. There's no reason why we couldn't a as a species and as our successors, whatever they are, machines even a survive into a very distant future and affect it.'

'But we're so small.'

'Yes,' I said. 'But ... but, look' a I was waving my arms, I was trying not to raise my voice a 'the scale of the universe is so unimaginably immense, in space as well as in time, and in all that we're the only thing that even knows it's there. There this ... this enormous, practically endless expanse of mindless matter doing its meaningless thing, gas contracting and fusing and exploding and all that, over and over, and here we are, a tiny, almost infinitesimal flaw in it all. A tiny, tiny crack of meaning and purpose and mind in an endless plane of meaninglessness. In fact, a crack is ... You know what happens when a single atom is out of place in a crystal?'

'Yes,' said Sophie, with the look of someone trying hard not to laugh. 'I'm doing materials, remember? Any force that's applied to the crystal gets concentrated on that atom, and soon there's another atom out of place, and so it goes on. That's how cracks get started. And once they start, they propagate. That's how scissors work and fabric rips.'

'Exactly,' I said.

'I don't see what this has to do with our significance.'

'Well,' I said, 'if even one atom out of place in a sheet of glass, say, can end up cracking the whole pane, just because we're small doesn't mean we can't have big effects.'

'You want us to crack the universe?'

'Yes,' I said. 'Or maybe, thinking about it as fabric, cut it into a shape more suited to ourselves.'

Sophie's cup rattled as she put it down. 'I see where you're going with this,' she said, looking me intently in the eye. 'If there are all these billions of years and lives to come a my God! It's like God! If you weigh it up like that greatest happiness of the greatest number thing-'

'Utilitarianism?'

'Yeah, OK, if we were to count in the happiness of future people, and we do ... Jesus fuck.'

'What?' I said, slightly shocked. I'd never heard her swear.

'It means anything we do to make sure humanity survives into this far future is right, no matter what so long as it works. Jeez.' Her smile glowed, as if from the back-light of trillions of happy future faces in the sky. 'I mean, even if ninety-nine per cent of the human race got wiped out, as long as there were enough left to have all these descendants, it would be worth it.'

'No, no!' I said, alarmed. 'I wasn't thinking that at all, you can't go sacrificing lives in the present for the sake of the future-'

'But we do,' she said. 'Well, states do. All the millions the US and UK and their allies killed in the war a all right, most of them not directly, so let's say caused to die if you want to be picky a and all the thousands of their soldiers who died, it's all justified in terms of reduced infant mortality and increased life expectancy and girls in school and women with jobs and cars and all that, right?'

'Are you winding me up?'

'It's what you believe, right?'

'Well, not-'

'You supported the war, didn't you?'

I had, much to my embarrassment and shame now. I couldn't even blame my parents: they'd always been opposed to it, in a passive, resigned way that had annoyed me and provoked me to my mid-teen pro-war pose. Only now, as a result of supplementary reading around my Sociology and Philosophy courses a the Ethics module had been gruesomely specific on torture, terrorism and the supposed justifications for both a had I come to see how deep and bloody was the pit from which we had so recently begun to climb.

'Oh come on,' I said. 'I was just a kid.'

'Fine,' she said. 'So what's your mature, considered view?'

I shrugged. 'Now that it's all over? I don't know. I wouldn't justify it in these terms anyway. Maybe self-defence-'

She laughed in my face.

'Let me finish,' I said, testily. 'That was how it was officially justified in the beginning a against nuclear and chemical and terrorist threats and so on. All I'm saying is that if they'd been telling the truth, they'd have had a point. All the humanitarian justifications came after it turned out they weren't.'

'All the same,' Sophie said, 'that's how it's justified now, isn't it? And the Second World War, too. So I'm not going out on a limb about how your idea about humanity's vast and glorious future might let us off all sorts of moral hooks now.' She gave a wry smile. 'Even if that justification turns out to be only made after the fact.'

'Yes, you are,' I said, feeling more secure. 'Out on a limb. Honest, Sophie, you've got even utilitarianism all wrong. Well, maybe first-order ...' I stopped and sighed at the thought of re-treading the first-year Ethics module. 'Anyway, look, the point is-'

'No,' said Sophie. 'You look, and let me tell you what my point is, OK, Ryan?'

'Yeah, yeah, I'm not-'

She took off her black leather jacket with a sinuous shrug and leaned forward a little, a movement that set the shiny material of her sleeveless top quivering. I made a polite and belated effort to keep looking at her in the face, which was itself fascinating enough, her dark-outlined eyes bright.

'The question I asked to start with,' she said, 'is what you want to achieve in life. You haven't answered that and to be honest I think you're evading it. I mean, all this stuff about the glorious future of humanity is all well and good but what's it got to do with the future of you?'

She said all this in a light, friendly tone. I found myself frowning, and opening and closing my mouth a couple of times.

'Well, all right,' I said at last. 'It's ... important to me because ... everything we do or don't do matters a heck of a lot because we're at the beginning of things, the ground floor so to speak, the foundation or maybe just the hole in the ground. And we've got all that responsibility a it's terrifying. But instead of living up to it and realising we're building this vast civilisation and maybe making ourselves fit to be part of it, whether we live into it or not, we're still squabbling about stupid shit like whether evolution happened or the climate is changing or which religion if any is true and so on.'

'No, we're not,' said Sophie. 'That's just the bloody nonsense of American electoral politics and in countries where Islamism is still a problem. Religion just doesn't come up anywhere else, and certainly not here, apart from a minority of students. So why does arguing about it matter to you?'

By now it was mid-afternoon. The coffee was cold, the Library Bar had gone quiet.

'Well,' I said, feeling painfully self-conscious, 'I think religion and cults and so on are being artificially stimulated in a very deliberate way to distract people from the economic crisis and all that. And I think my ... what I want to do is fight that, help make people see what is really going on.'

'Artificially stimulated?' Sophie looked interested. 'How?'

'I think some of the UFO phenomena are secret aircraft and UAVs and so on, and that they have some kind of electrical effects that stimulate the temporal lobes a the parts of the brain that can give people religious experiences.'

She just stared at me. 'That seems a bit ... far-fetched,' she said, in a tone that suggested she was keeping careful control of her voice. 'And a bit redundant as an explanation, seeing as the social and psychological reasons why some people have these weird beliefs and experiences are ... pretty much well understood, you know?'

'Uh, yeah, but-'

'And anyway,' she added, 'even if it is happening, what makes you think you can do anything about it a by arguing with spotty-faced fundy students at stalls on your way to lunch?'

I opened my mouth, then closed it again. I didn't know what to say.

This wasn't because I didn't have an answer. I had one, right on the tip of my tongue. It was this: because the Space Brother and the Space Sister told me.

Don't get me wrong a I knew very well that the Space Brother and the Space Sister were figments of my imagination. But my private explanation of those figments seemed, now that I was on the verge of uttering it, even more bizarre: they were planted there by a secret faction of the rational elements of the secret rulers of the world.

Jesus H fucking Christ, I thought. My one-man mission to promote rational thought against religion, pseudoscience and the paranormal was rooted in a UFO encounter, a single vivid dream that still seemed real in a way my frequent nightmares and abduction experiences didn't, a phone-camera pic allegedly of a page in a conveniently inaccessible book, and a conspiracy theory that curled up and died on my lips out of sheer embarrassment the moment I found myself about to expound it.

Suddenly the whole thing stank with the squalor of the occult.

'Well, now that you mention it,' I said, with a half laugh that I hoped sounded self-deprecating, 'it does seem a bit disproportionate, doesn't it? And my UFO theory a well, it's not just mine, and I think it's worth looking into, but you do have a point. I mean, if something like that was going on, the best thing I could do would be to encourage people to wear tinfoil hats.'

'Tinfoil hats,' Sophie said. 'Yes, that just about sums it up!'

'Oh, well,' I said. 'Fancy another coffee? Let me get it this time.'

Sophie shook her head. 'Nah, thanks, but I've got a lecture in half an hour, and I need to nip into the library first.'

'Aw, right. I owe you one, then.'

She shrugged into her jacket and gathered up her bag and books. Just before she left she turned to me and said, 'You look after yourself, Ryan, OK?'

'OK,' I said.

'I mean that,' she said. 'Look after yourself. Stop worrying about saving the human race. Get a bit better acquainted with a few more of its members, right?'

'Right,' I said. 'I see what you mean.'

What she'd said sounded like good advice. It would be easier to take than most such, because she'd just pulled the rug from under my entire sense of purpose in life.

She looked at me quizzically for a second or two, blinked, shook her head slightly, then smiled and left, leaving a faint trace of her scent and a nagging sense of a missed opportunity and a missed point. Had she been suggesting that I get better acquainted with her? For a minute or two I contemplated running after her, catching up with her before she'd walked the hundred metres to the library, and asking her ... what? Out for a drink? And what if she turned me down? And what if she were still with Calum? And what if ...? By the time I'd war-gamed the possibilities in my head, the moment for the action in reality had passed.

I looked at my watch. The time was a quarter to four. I had a seminar on Middlemarch at four in the David Hume Building, less than five minutes' walk away. I had made extensive notes for it on my phone.

Fuck you, George Eliot, I thought. I needed time to think. I strolled to the bar and ordered a double single malt.

'Let me get that,' said a voice behind my shoulder. 'And the same for me, please.'

I turned, and saw a man a few years older than myself wearing a black suit with an open-necked blue denim shirt.

'Good to see you again, Ryan,' he said, sticking out his hand. As I shook it, he grinned and added, 'You look a little perplexed. Perhaps you don't remember me.'

'Oh, I remember you all right, Reverend Baxter,' I said.