At one point, mysteriously, Henry said to Philip, 'He's not coming.'

At midnight, the fireworks went off over the river. The seven friends, a modest number, clustered around the one west-facing window. Synchronized flowers of light bloomed and sparkled, reflecting on the canal. To Michael they seemed to come erupting out the imagination, from the potential of the people who had designed them. He imagined them in their timeless aspect, forever a blurring of sequinned light, moving and still at the same moment. The fireworks looked like the self.

Someone, completely naturally, placed a hand on his shoulder and left it there. It was padded and hot. Michael turned around and it was Lee.

They toasted the New Year. They toasted absent friends: the mathematician had lost his partner two years before.

Michael liked them all. He hadn't known one of them, but before the end of the evening, he passed around his card, and got three in return, including Lee's. About one in the morning, the first guest stood up to go. Michael remembered the tubes, and was thinking about leaving as well, when the doorbell rang.

Philip and Henry each cocked an eyebrow. A voice barked up the answer phone. It sounded sinewy and smooth and reassuring. Philip looked back at Henry, his eyes wide and gleaming, and Philip nodded quickly, yes. He waited at the top of the stairs. 'Hello, hello!' he said.

'Sorry, but I had my sister's party to go to,' said a breathless voice, and Philip seized a hand and pulled in Henry.

Only this was Henry with slightly longer hair, wearing a brown sweater with a hole in it.

This is him,' said Philip. 'Michael. Meet the real Henry. This is Stumpy.'

Stumpy perked up. 'So. You're the magic man,' he said. His cheeks were redder than Henry's and the mushroom smell was stronger.

'Ah. Ah, yes.' Michael looked back at Henry, and all three of them – Henry, Philip and Stumpy – laughed.

'I told you once that Stumpy would love to know about this,' said Henry.

And Henry and Stumpy gazed at each other, grinning and slightly dazzled. Stumpy wobbled slightly in place and Henry had to catch him, and they were brotherly in each other's arms. And Philip cuddled Stumpy too, partly to keep him standing.

'I had a bit too much at my sister's,' Stumpy said, chuckling.

'He's staying with his sister. She lives in Camden Town too.'

'It's a long trip from Camden Town,' said Stumpy.

Michael asked, 'How did you get together?'

'Henry wrote me a note and said he was my long-lost twin, and sent me a photo of one of Philip's paintings of him.' Stumpy mimed amazement. 'So we met, and he told me all about you. How does it work?'

Michael heard himself say, 'The universe is twisted out of nothing by gravity. And I think I will be able to prove that thought and gravity are the same thing.'

'Wow!' Stumpy's eyes widened and he laughed with a kind of pleasure, while shaking his head. Michael realized he hadn't told Henry anything about his new research. He wanted Henry, particularly, to understand. 'I've got a new project. I think I can describe what has happened using equations.' Henry reached forward and gave Michael a kind of hug that turned into a shake of approbation. Michael looked at Stumpy and found he was embarrassed. 'I mean, I think I can do it. I don't know yet. I've still got to do the work.'

'It sounds fairly mind-blowing,' said Henry.

'I wish my head was a bit clearer,' said Stumpy.

'We've got other guests,' said Henry pointedly to Philip. When Philip didn't move, Henry pulled him away.

And for some reason Michael regained his old clarity. He had forgotten his talent for turning science into words. Michael sat with Stumpy on the futon sofa. He explained how he would apply the equations used to describe black and white holes. He explained that in the fifth dimension the equations that describe electricity also describe gravity. 'And thought is a matter of changing electrical charges.'

'Oh!' said Stumpy, and fell forward holding his head. He sat back up. 'If you did that, you might end up proving that God exists.'

'I might end up proving that He doesn't,' chuckled Michael.

Stumpy was younger than Henry. His smile was brighter, his enthusiasms more overbearing, his words more common and less distinct. Michael looked at Henry and pondered what that meant.

You're wiser than your original model, Henry. Of course, you're timeless. You are as wise as you will ever become. And does that mean you know what will happen? Or, rather what is likely to happen?

Michael looked back at this bright and cheerful, confident 24-year-old. It was like looking at old photographs of friends. You would need me more, Michael thought. I could even help you grow into becoming Henry.

It was nearly two o'clock. 'Well, I've really got to go,' Michael said. He kissed them all on the cheek, and hugged Henry and Phil together in a heap. 'Thank you, thank you, thank you!' he said. Stumpy looked a little wistful as he shook Michael's hand.

And suddenly Michael was back out in the night. Luck was with him: the evening seemed somehow warmer than the day and he did not have a long wait for the train. He heard it whining towards him, even as he climbed the station staircase.

The train doors whooshed open to show a car that was nearly empty. Past Canary Wharf, it began to fill with people. A gang of Indian lads in fleece jackets and trainers got on at West India Quay. They all had helium-filled balloons. The balloons were metallic, in the shape of dolphins. At the next stop, a merry black girl bounced in as lightly as the balloons, turning and laughing with her elegantly groomed friends. At Westferry two groups arrived, ebullient new City lads in modern fabrics who sang Abba songs against a competing group of what looked like nurses.

Michael was one of the oldest people there. He watched secure and detached from his early found seat, and settled into a kind of contented concentration.

He seemed to go on settling deeper and deeper. The settling almost made a sound. It would have been a sound like rain.

What were falling were impressions. The black girl had done her hair in perfect rows. The Aids-awareness ribbon on her coat was in fact an enamelled broach. Michael pondered the generosity that impelled her to take up permanently a cause that many people would think was someone else's. The Indian boys began shyly to offer people their balloons. They gave one to Michael.

Michael thought of his chicks. 'We ought to let them all go free,' he said to one of the lads.

'That'd be great. People'd look up and see all these dolphins up in the sky. They'd go like, oh wow, the sky is full of dolphins.'

It seemed to Michael that it was an inspired thing to say. 'I wouldn't let this one go if you don't want me to.'

'Do what you want, man. It's a party.'

Everyone, Michael included, got off at Bank to change onto the Central Line tube. There was a long, long wait for the train. A raucous bevy of young women stood near Michael. They were plump, pale and nearly nude, all in the common fashion of tight trousers, peel-off tops with little straps and shortish hair parted in the middle. They showed off pastures of perfect white shoulders, a sacrifice in winter. They had all written on pieces of paper, which they had taped to themselves. 'Innocent,' said one, 'till proven guilty!' Another said, 'Free to Good Home.' They were all more than a bit pissed and had done something extremely daring in either a pub or a party and couldn't stop talking about it.

When the train came, the girls all ran, though they didn't need to, the thick heels of their shoes clopping like horses' hooves. They swept themselves and Michael into the carriage on a gust of giggles.

Michael sat down and let everything rain around him.