The best photographs of all would be on a beach, on holiday, with something to occupy his awkward hands. It would be apparent then that Michael had the body of an athlete. He was a big, broad-shouldered man. Because of the flattening of his broken nose, his face was rugged, like a boxer's. Michael could look unbelievably butch.

There was one photograph from Michael's youth.

It was hidden away, unsorted. Michael would not be able to find it now. He didn't need to. Michael carried it around with him in memory. He could always see it, even when he didn't want to.

His father had taken it from a riverboat in California, during their last summer together. In the photograph, Michael is sixteen years old and is quite possibly the best-looking person on the planet. He is certainly one of the happiest.

In the photograph Michael sits in a dinghy. He's laughing and holding up a poor pooch of a dog. She was called Peaches the Pooch. Peaches gazes miserably out from under a thick coating of river-bottom mud. Michael's thighs and calves are also covered in mud. Even then he was a big lad, with wide shoulders and lines of muscle on his forearm. His black eyes are fixed directly on whoever is taking the photograph and they are wide with delight. His face is nut brown, like an Indian's, and his smile is blue-white in contrast. His black hair has reddish-brown streaks from constant sunlight. Sunlight glints all around him on the slick, brown water and onto his face, which is indisputably happy.

If you look closely, the nose isn't broken.

By the time that photograph had been developed and posted back to England, it was winter. That summer Michael on the Sacramento River was already history. Michael remembered opening the envelope. There was no letter inside from his father, just photographs, that photograph.

It should have been the moment when Michael learned to love himself. Like every teenager he had been gawky and spotty. It should have been the moment he left doubt behind, and finally accepted that he was beautiful.

Instead, all Michael could do was regret. The beauty, he felt, was a mask. He'd been hiding behind it. It was better now, being ugly. It was closer to the truth. Michael made himself ugly.

The photograph was the last thing he ever had from his father. He knew what his father was saying: this is who you could have been.

Everything changed without Michael noticing at the time. In the summer, he had been determined to be a vet. Now he was a scientist, who experimented on animals.

The summer Michael had enjoyed acting; had been in a drama class for fun, and took the lead role in all the plays. He had a way of conjuring up old ladies, terrified spivs and policemen out of his own body.

In winter, Michael seemed dispossessed of his own body.

This made him mostly harmless. Women liked him; his students liked him. He always kept a distance from them. It was not that he was afraid of women or students, exactly. He was afraid of how he became around them. He knew he could be waywardly funny, exact, truthful. But then something would happen, and power would withdraw from Michael like the tide. Beached and helpless, he would fumble and make mistakes and let himself down. He would forget things, like appointments or his glasses. Uncomfortable, he would grin and grin and grin.

Michael was impotent. If this were symptom or cause he could not distinguish. He didn't care. Impotency meant that only the most brutal and depersonalized of sexual episodes were safe enough for him. Only parks or toilets or saunas could hide him.

If his partners had no idea who he was, how could they hurt him? If they could hardly see him in the dark and didn't know his name, there could be no embarrassment when he didn't get it up. They didn't care if Michael got it up. They were too terrified of police to notice and too desperate to come quickly. It all stayed hidden and detached.

But it relieved the pressure. It relieved the pressure of living with someone who gave him no sexual satisfaction. It relieved a kind of erotic itch, which he could never satisfy, and had not been satisfied for more than twenty years. Michael was 38 and his very skin crawled with lust.

A quick jerk off in a car park, a slap on the ass in bushes in a park provided cessation and a masturbatory climax but no satisfaction. So he would have to go back again, to a sauna or a cottage. And then, again. This is addiction. Michael was a nice man who was addicted to speedy, functional sex. He kept this shut away from the rest of his life.

In the rest of his life, he offered the world sweetness, integrity and intelligence. He placated life. He worked himself nearly to death.

Michael had a contract to teach biology two afternoons a week. He prepared his lectures and marked papers, just as if he were full-time, only he was paid less.

He joined academic committees and fought for new IT networks. He joined Boards that recruited new teachers and exposed his bitter elders when they said, untruthfully, that a candidate for a post had been fired from her previous position.

Michael lifted weights and read all the journals in his field and did desk research. He became a rising star in his field, producing publishable papers in biology from scanning work in two fields and bringing them together. Somehow this still resulted in very little extra money.

The two fields were neurology and philosophy, the grey area where biology was helping philosophers answer questions such as: do we have a soul? What is the self?

Michael understood how we see. Images are formed from millions of separate stimulations in the brain: one area responds only to vertical lines; others to angles; others to oncoming movement. Others are tickled by symmetry of any kind, or by green or pink. Still others react to shadow; whole other areas bring together the slightly different angles provided by two eyes.

The brain responds to verbs of movement, adjectives of colour, and nouns of space and shape. We spend our first six months learning to read these complex sentences.

Could the grammar of language have its origins in the grammar of sight? If so, then how could people blind from birth learn to talk? What if grammar came before both vision and speech? Michael wrote papers on the subject. They were influential. People were surprised that he was not a professor.

In the spiritual space where ideas were formed, Michael had power. He found power in snatching those ideas out of air and putting them to paper with rattling keystrokes. Michael wrote all weekend long.

In order to answer those people who insisted on modelling the living brain on circuit diagrams, Michael was taking a conversion degree in Computer Science.

So, as if he did not have enough to do, Michael was learning how to program in C and studying how the registers of computer memory worked. He had to turn in programs to a colleague who opposed his views on what networks the students needed.

The programming module alone took ten extra hours a week. When major coursework was due it would be twenty extra hours a week. Having worked all day, he would work all night, and when finally the program worked, he would weep from joy, as if he had climbed Mount Everest. That was the payoff. He had a blazing moment of joy. Two hours later, he crawled out of bed, and it all began again.

Sometimes, Michael saw friends. He would arrive late at their houses, streaming cold air and apologies and feeling awful because he hadn't been able to organize buying a bottle of wine. His boyfriend Philip would be there waiting for him in worn silence. Perhaps everyone had already begun the first course.

'Michael's always late – we told you he would be!' his hosts would exclaim, laughing and admonishing. Michael's smile would flick like a switchblade with annoyance. The blade cut both ways: himself and his friends.