'You've never noticed how you group sandwiches into Venn diagrams?'

'Do I?'

'It's why I married you.'

I remembered the little knuckle of meat Maisie had given me for my wart. I took it out of its silver paper, resisted a fleeting temptation to pop it into my mouth, and rubbed it against my wart.

'Excuse me a moment, John. I have to bury a little bit of meat.'

'Maisie's wart cure? Go ahead. I won't peep, Scout's honour.'

I will arise and go now, and go to Innisfree, And a small cabin build there, of clay and wattles made: Nine bean-rows will I have there, a hive for the honeybee, And live alone in the bee-loud glade.

'I haven't thought about Physics for a whole thirty minutes.'

'The old Clear Island magic. Is anyone looking?'

'No. We have the whole hillside to ourselves. And the man in the afternoon moon. And Noakes's Jerseys.'

'Then come here, my ocean child, my buxom island wench...'

'Buxom! John Cullin...'

We left The Green Man before teatime. John, Planck and me, walked back to Aodhagan. Liam standing on the pedals of his mountain bike.

'So where did you learn to hold whiskey like that?' I asked Liam.

'Da.'

'That's scurrilous slander is that!'

We walked on, Planck the only one who could walk straight.

'It's a rare old sunset tonight, Da.'

'Is it now? What colour is it?'

'Red.'

'What red?'

'Inside of a watermelon red.'

'Ah, that red. October red. That's a rare old sunset.'

I'd left John by the gate sitting on a stone with Planck. The turf was pucked with hoofmarks and molehills. Liam cycled on ahead to give Schroedinger his dinner.

The garden was now a little forest. I was right, the roof had fallen in. I picked a way down what might have been the path. Were eyes behind the murk-glazed windows? The ivy on the walls rustled. Something inside clattered and flapped. Owls, bats, cats, bipeds up to their own business?

'h.e.l.lo,' I said, on the doorless threshold. 'Anyone there?'

My da collapsed with his silted-up heart, just here. With the deadly calm of a person who had seen the future, my ma told me to look after him while she bicycled down to the harbour to get Dr Mallahan.

Da had wanted to say something to me. I leant close. He spoke like he had a ton of bricks on his ribs. 'Mo, be strong, you understand? And study hard, and don't let your Gaelic lapse. It's who you are.'

'Are you going to die now?'

'Aye, Mo,' said my da, 'and I can tell you, poppet, it's an intriguing experience.'

It had been a neat little house, smelling of fresh air and fresh plaster and bleach. My da had tiled it himself one summer, with help from the Doig boys, Father Wally and Gabriel Fitzmaurice who drowned that same October. We'd made a huge bonfire from all the old thatch, down on the beach.

But any given system will decay from a complex order to a simpler condition. After my mother and I left Clear to enter the world of aunts on the mainland, storms and woodworm got to work. Other islanders needed building supplies themselves. My ma couldn't face her ghosts, so she told everybody to help themselves.

Now twigs hold up a roof of twilight and early stars.

'Mo!' John is calling from over the fields. 'Are you okay?'

No messages were left.

'Yes,' I shout back, zipping up my anorak.

John made a yawling noise as he stretched himself awake. A mild day, rarefied by wintriness. I heard helicopters. 'Sleep well, my love?' John hears smiles in voices.

He degummed his mouth with his tongue. 'Aye. I had this dream. I was floating in a shallow sea in Panama, no idea why it was Panama, it just was. I could see the light on the inside of the waves up above, and around me little puffy clouds were moving. "That's odd," I thought. "You can't have clouds under the sea." And when I looked closer, the clouds were jellyfish, Christmas-tree light-coloured, all glowing on and off.'

'Nice dream.'

'There are three times when I don't feel blind: when I show people around Clear Island; when I beat Father Wally at chess; and when I dream colours... Mo?'

'Yes, John?'

'Mo, what's up?'

Huw told me that you always wake up a few seconds before the earthquake starts.

'It's today.'

I interact with John, the Texan, Heinz Formaggio and the rest of reality in the way that I do because I am who I am. Why am I who I am? Because of the double helix of atoms coiled along my DNA. What is DNA's engine of change? Subatomic particles colliding with its molecules. These particles are raining onto the Earth now, resulting in mutations that have evolved the oldest single-celled life-forms through jellyfish to gorillas and us, Chairman Mao, Jesus, Nelson Mandela, His Serendipity, Hitler, you and I.

Evolution and history are the bagatelle of particle waves.

Liam came in and swigged a bottle of milk straight from the fridge. 'Maybe they're going to leave you be, Ma.'

'Maybe, Liam.'

'Really. If they were going to come and get you, surely they'd be here by now.'

'Maybe.'

'If that happens, could you get a job at the department at Cork? Could she, Da?'

'The vice-chancellor would get down on his very knees, Liam,' said John, his voice upholstered with tact, 'but-'

'There you go, Ma.'

Ah, Liam, the most malicious G.o.d is the G.o.d of the counted chicken.

The Trans-Siberian shunted through a slumberous forested evening in northern China. I was still toying with matrix mechanics, but getting nowhere. I'd been stuck with the same problem since Shanghai, and now I was wandering in circles.

'Mind if I join you?'

The dining car had emptied. Did I know this young woman?

'Sherry's the name,' said the Australian girl, waiting for me to say something.

'Please, take a seat, let me move this junk for you...'

'Maths, eh?'

Unusual for a young person to want to talk with an oldie like me. Still, we're a long way from home, and don't generalise, Mo. 'Yes, I'm a maths teacher,' I said. 'That's a thick book.'

'War and Peace.'

'Lot of it about. Particularly the former.'

A half-naked Chinese toddler ran up the corridor, making a zun-zun zun-zun noise which may have been a helicopter, or maybe a horse. noise which may have been a helicopter, or maybe a horse.

'I'm very sorry, I didn't catch your name.'

I felt a stab of suspicion. Oh, Mo! She's just a kid. 'Mo. Mo Smith.' Mo!

We shook hands. 'Sherry Connolly. Are you going straight to Moscow, Mo, or stopping off ?'

'Aye, straight through to Moscow, Petersburg, Helsinki, London, Ireland. How about you?'

'I'm stopping off in Mongolia for a while.'

'How long for?'

'Until I want to move on.'

'Good to be out of Beijing?'

'You bet. It's good to be out of my compartment! There are two Swedish guys, they're drunk and having a belching compet.i.tion. It's like back home. Men can be such drongoes.'

'I could get your compartment changed. Our babushka's tame. I bribed her with a bottle of Chinese whisky.'

'No worries, thanks. I grew up with five brothers, so I can handle two Swedes. We get to UB in thirty-six hours. Plus, there's a hunky Danish guy in the bunk below me... You travelling alone too, Mo?'

'Yes, all alone.'

Sherry gave me that look.

'Great heavens, no! I've got a husband and a teenage son waiting at home.'

'You must be missing them. They must be missing you.'

What a perfect pair of sentences. 'Yep.'

'Hey, I've got a flask of Chinese powdered lemon tea. Join me? It's the real McCoy.'

It was nice to speak to a woman in my own language again. 'I would love to.'

We talked until we got to the Mongolian border, where the train's wheels were changed to fit the old Soviet gauge, and I realised how lonely I had become.

Maybe it was just the caffeine in Sherry's tea, but when I next glanced at the black book I saw how utterly obvious the answer was: Trebevij's constant broke the logjam. Mo, you're a deadhead. I worked for what seemed a little while longer, and before I knew it the dining-car staff were starting the breakfast shift.

The islands, cities, forests, all left behind. Dawn welled up over the open gra.s.slands of central Asia. I was an extremely tired, middle-aged, morally troubled quantum physicist with a very uncertain future, but I had gone somewhere no one else had ever been. I wobbled back to my compartment and slept for over a day.

Accepted wisdom accuses Dr Frankenstein of hubris.

I don't think he was playing G.o.d. I think he was just being a scientist.

Can nuclear technology or genetically engineered parsnips or quantum cognition be 'right' or 'wrong'? The only words for technology is 'here', or 'not here'. The question is, once here, what are we going to do with it?

Dr Frankenstein did a runner, and that was his crime. He left his technology at the mercy of people who did what ignorant humans habitually do: throw stones and scream. If the good Doctor had shown his brainchild how to survive, adapt, and protect itself, all that gothic gore could have been saved, and transplant technology jumpstarted two centuries early.

I see what you're saying, Mo, but how can you teach an engine to recognise right and wrong? To arm itself against abuse?

Look at the black book. If Quancog isn't sentience, give me another name for it.

The telephone rang as I cracked my egg. It was next to John, so he answered. 'Billy?'

John said nothing for a long time.

Bad news.

'Right-o.' He put the receiver down.

I knew it.