"He remembered nothing for more than a few seconds. He was continually disoriented. Abysses of amnesia continually opened beneath him, but he would bridge them, nimbly, by fluent confabulations of fictions of all kinds. For him they were not fictions, but how he suddenly saw, or interpreted, the world. It's radical flux and incoherence could not be tolerated, acknowledged, for an instant -- there was instead, the strange, delirious, quasi – coherence, as Mr Thompson, with his ceaseless, unconscious, quick-fire inventions, continually improvised the world around him."

"The Man Who Mistook His Wife for a Hat and Other Clinical Tales', by Oliver Sacks.

Dr Oliver Sacks is a clinical neurologist who has turned his case histories into haunting short stories. 'The Man Who Mistook His Wife for a Hat... Is a collection of stories about individuals with mysterious neurological quirks: patients unable to recognise the people around them, patients who have lost their memories, patients whose hands or legs or arms have become alien, as if disconnected from them.

What has happened to these people is "at the very edge of the imagination" but Sacks makes his clinical tales so vivid and evocative that they seem to resonate with echoes of our own experience. After its release in paperback in the United States 'The Man' recently went to the top of the bestseller lists and the book is now available in Australia.

When we met at his house in New York, Sacks himself launched straight into an engaging performance. A big, bearded Englishman with wisps of whitish hair sticking up untidily above the spectacles parked high on his forehead, he bounded around the house, picking up the articles and books that he wanted to give me, and pausing, midflight to explain something about a patient of his whose paintings were propped up on the piano. He misunderstood a question and burst into laughter, briefly sounding every bit as Falstaffian as he can look in his photographs. From the kitchen, he apologised, humorously for being without the basics.

"There's no drink," he called out, "and no tea. Would you like some ox tail?"

"Oxtail?" I had trailed in after him. "The best part of the ox," he said, straight-faced, throwing open the refrigerator door, as if to prove it. Instead, he made coffee, and talked and talked. The torrent of words failed to hide his diffidence.

He was skittish, and you could imagine him receding, if the situation call ed for it. Sacks is the Professor of Clinical Neurology at the Albert Einstein College of medicine, but I thought of him, somehow, as most at home with his patients. Where other doctors will bristle with authority, Sacks listens to his patients, and listens intently.

His book 'Awakenings', first published in 1973, charted the effects of the drug L-Dopa on a few survivors of the sleeping – sickness epidemic of the 1920s, people frozen for decades in a state more like death than life, "profoundly isolated, deprived of experience, half-forgetting, half-dreaming of the world they once lived in".

Many were afflicted with Parkinsonism. "My essential symptom," a patient he called Frances D. told Sacks, "is that I cannot start and I cannot stop. Either I am held still or I am forced to accelerate. I no longer seem to have any in between states."That, wrote Sacks, "sums up the paradoxical symptoms of Parkinsonism with perfect precision".

The poet W.H. Auden called 'Awakenings' a "masterpiece". Harold Pinter was to turn one of its extraordinary biographies, the story of 'Rose  R. Close' into a play called ' A Kind of Alaska'. With L-Dopa, Rose R. was brought back, as if from the dead, like the other post – encephalitic patients long entombed in the institution, except that she came back briefly, as the flapper eshe had been when she fell ill in 1926.

She made allusions to figures prominent in the 1920s, she recorded lewd songs and light verse from the era, and stayed in her room, engrossed in her memories, doing her best not to notice anything that had happened since. "I suppose one calls this ' forced reminiscence', or incontinent nostalgia," wrote Sacks.

In his work, the artist's imagination is reconciled with scientific rigour. Indeed, at every opportunity, Sacks argues for a "romantic science" that takes its cues from the clinical tales of the 19th Century, instead of the "lifeless abstractions" of today's neurological science, from which the individual is more or less missing.

Sacks showed me part of the film of 'Awakenings' made by Yorkshire Television. In the film, Rose, who had often sat motionless in her wheelchair for hours on end, whose face had been "completely masked and expressionless", was playing the piano, while another patient who had been among the living dead was dancing.

Rose, whose state of giddy animation did not last long, has since died. The people in the film were wraiths, but they seemed to be all around us.

Sacks lives alone in City Island, a former fishing village connected to the mainland by a drawbridge. Though the island is at the water's edge of the Bronx, in New York City, it has the other-worldly air of a resort. In mid-winter, with the garden still covered in snow, his house seemed as snug as a ship's cabin. There were books everywhere, bookshelves in every room.

The paintings propped up on the baby grand in one of the downstairs rooms were abstracts. Some were in colour, some were in black and white. In front of the paintings was an arrangement of fruit, made in clay and painted in mottled leaden greys. The artist, one of his patients, has become completely colour-blind. Finding it difficult to explain the way the world now looked to him, "he decided to make an entire universe as if moulded in lead," said Sacks, who is writing a book about him.

"Things came on him after a head injury which may have affected the cerebral circulation. There's a terrifying description he gives of driving to work in the morning with everything suddenly seeming misty and greyish. He was stopped by the police for going through three red lights. Most of his paintings are brilliant colour abstracts. When he got to his studio, his whole life was there, sort of meaningless.

"He felt terrified, finished as an artist. He tried to paint in colour when he could no longer see colour." Sacks showed me one attempt, a murky, messy, amateurish-seeming painting of flowers that shows up, in intricate detail, only if it is photographed in black and white.

"Over there is the first black and white painting he did, and you see that it's full of staring, blinded, averted, haunted faces, sort of framed, struggling for control in the chaos."

The painter wrote to him after reading a review of 'The Man Who Mistook his Wife for a Hat'. People do it all the time. Something like 5000 patients and would-be patients write to him each year. Hundreds of people send him proofs, manuscripts and theses.

"I'm beginning to go a bit batty with it," said Sacks, who is getting someone to help him sort out his correspondence and fend off the insistent appeals. But the painters letter "got through to me. His situation is extraordinary.

"One thinks of the whole world, in all its wealth of form and colour and movement and meaning. In health, you've no idea of what goes to create a reality. You have to see someone for whom image and meaning or movement have dropped out."

Because of a stroke, one of his patients can no longer see movement. "What she sees is a succession of stills, but there are gaps.

A car she has seen a long way off while crossing a road is suddenly much to close. If she's with company, people appear and disappear in parts of the room. When she tries to pour coffee, or water from a kettle, she sees a sort of solid glacier. The cup stays at one level and the next second is over-flowing.

"You think of the sense of movement as a given a priori. Indeed, if you do stop to think about how you walk you can't walk because action is beyond analysis. You can't walk by thinking about it" 

Sacks wrote about just that in 'A Leg to Stand On', a terrifying account of his experiences as a patient, after he had injured his knee in a mountaineering accident. He kept notes, of course. He writes as if storytelling is second nature to him, and perhaps it is.

Sacks grew up in London. Both his mother and father were doctors. "My mother's medical stories would enchant the gardener and the milkman for hours on end and I would see the milkman frozen, almost catatonic, halted in his rounds for one of my mother's stories of  case histories with novelistic elaboration, my own sort of clinical tales."

This father, a GP, still does a couple of surgeries a week at The age of 91. His three brothers and doctors. Marcus, the eldest, longed to be an Orientalist, instead became a doctor, because of the war, and ended up as a GP in Paddington, in Sydney, speaking Chinese to his Chinese patients, and Japanese to his Japanese patients. Yes, said Sacks,  he had visited him in recent years. Paddington reminded him of Victorian London, or perhaps the east end of London where his father had practised in the 1920s. He paused and there was that great gust of laughter. "A tropical Whitechapel," he said, "with those out rages tree ferns.

"Last year, I went to the Barrier Reef and farther north, finding tree ferns for which I have a grand passion," he chuckled, "a secret passion. People kept saying 'Look, you ought to see Melbourne', but I'd be off looking for tree ferns.

"I had a need for primordial landscapes, pre-human landscapes of one sort or another." In 'Migraine', his first book, he quoted Sir Thomas Browne: "we carry with us the wonders we seek without us: there is all Africa and her prodigies in us."

"I wanted to convey that sense of neurological landscapes," said Sacks, "of Africa's and Alaska's and Arctics and Australias. I was going to use all sorts of Australian metaphors in 'Hat' because it's about a neurological Australia, tipsy-turvydom, the antipodes of human nature."

In fact, almost anything will start him off on a story. "There is something in the clinical imagination which is like the novelist's imagination. Thousands of stories are floating around. You've forgotten, they're unconscious, and suddenly something brings them out. The smell of eucalyptus in the Presidium in San Francisco suddenly brought out 'The Dog Beneath the Skin' (a story in 'Hat)'."

Sacks writes in planes, in trains, in inns, in other people's house. "One would think that the silence and solitude of my own little cottage would be the right place but, I,uh, don't find it very easy to settle down here and write. I want movement and life around me.

"Two of the pieces in 'Hat'-'The Possessed' and 'A Matter of Identity' - were actually written on the same night, at Sammy's, a seafood restaurant at the end of the street.  One of the reasons I'm so fat, I get sort of shy about sitting in a restaurant for eight hours and I feel I keep having to order more and more food."

In Sammys somewhere between the linguini with hot sauce and the cheesecake, he wrote about Mr Thompson, the former grocer with Korsakov's Syndrome, who had lost his memory, and with it, all  sense of his identity."To be ourselves, we must have ourselves--possess, if need be re-possess, our life stories. We must 'recollect' ourselves, recollect the inner drama, the narrative, of ourselves. A man needs such a narrative, a continuous inner narrative, to maintain his identity, his self."