The final stage of life, Dante wrote, is like a ship, gradually lowering its sails at the approach of the harbour. It is a serene image of destination — and eminently unfit to characterize the final decade of Oliver Sacks's life. Against a tide of diminishing health, he added four books to an already impressive catalogue: Musicophilia (2007), The Mind's Eye (2010), Hallucinations (2012) and — only months ago — On the Move, a candid sequel to his childhood memoir Uncle Tungsten (2001). Several more books are nearly finished.

Credit: Elena Seibert/Corbis Outline

Oliver Wolf Sacks, who died in New York City on 30 August, was born in London in 1933 into a large Jewish family. His father was a general practitioner, his mother a surgeon. His aunts and uncles were inventors, chemists and physicians. He grew up with the sense that it was a family duty to be 'scientific'. In 1939, at the start of the Second World War, he was sent away to a boarding school in the English Midlands. Sacks, who would rather have been in danger with his family than safe without them, spent four miserable years there. The experience scarred him for life: “sent away” is how he put it 75 years later in the opening sentence of On the Move.

Reunited with his family in 1943, Sacks developed a passion for chemistry. Although he eventually chose to study medicine, contemplation of the periodic table never ceased to soothe him in times of turbulence. Sacks studied at Queen's College, University of Oxford, UK, qualifying as a physician in 1958. He left for the United States in the early 1960s and began five years of medical training, interspersed with riding motorcycles, working out in gyms, experimenting with amphetamines and lifting weights on Muscle Beach, California. When a stint in a neurochemistry lab ended with a resounding, “Sacks, you are a menace in the lab! Why don't you go and see patients — you'll do less harm”, he decided to do just that. In 1965, he took up consulting at Beth Abraham Hospital in the Bronx, New York.

In its wards he encountered some 80 survivors of the 'sleepy sickness' pandemic of the 1920s. He found them to be frozen, mostly, in a statuesque, 'parkinsonian' state. High doses of the Parkinson's disease drug L-dopa 'awoke' them from their lethargy, but — as indicated by their vocabulary, likes, dislikes and skills — in a state of mind belonging to 40 years before and in a world that was no longer theirs. Sacks noticed such diverse reactions from patient to patient that he adapted what was initially intended to be a conventional double-blind trial to a series of case histories, which he published in 1973 as Awakenings.

After reading Awakenings, Russian neuropsychologist Aleksandr Luria sent Sacks a letter. He praised Sacks's talent for observation and description, which reminded him of the nineteenth-century tradition of the neurological narrative. Much of what was to become vintage Sacks unfolded from this book. His work was case-oriented rather than population based, descriptive and intimate rather than detached. And he wrote books, not series of papers in neurological journals. To this he added his signature approach of making house calls. He tried to meet his 'cases' in their natural surroundings. He observed, for example, a surgeon with Tourette's syndrome while he was operating; visited Temple Grandin, a woman with autism, in her office in the animal-sciences department of Colorado State University in Fort Collins; and immersed himself in the world of deaf culture.

The case histories in The Man who Mistook His Wife for a Hat (1985) secured him a worldwide audience. It also helped to articulate his scientific credo. Taking inspiration from German neurologist Kurt Goldstein, Sacks came to think of neurological disorders as challenges to finding a new equilibrium. In response to injury or disease, people go through a phase of adaptation and reorganization, often mobilizing inner resources that have previously lain dormant. According to Sacks, it is the physician's task to help patients to achieve a new order by being sensitive to these altered orientations.

As Sacks indicated in On the Move, growing up at a time when homosexuality was still listed as a mental disorder by the American Psychiatric Association alerted him to the sometimes detrimental consequences of psychiatric labelling. Rather than locking individuals in a 'condition', he took the upbeat perspective of pointing out the benefits over the deficits — sometimes to the point of eclipsing the original pathology. In many cases, this had a liberating effect: one may have Tourette's syndrome and still become a surgeon, or, like Grandin, have autism and have a career in science. Sacks thought in terms of neurodiversity — the idea that conditions result from normal variation — well before the term became common among those who distanced themselves from the medical perspective on autism.

Sacks saw himself as a storyteller, not a theorist. He often said that he was happy to present the case material that others could use to devise grand theories. But each story, of course, is a theory. Like Goldstein and Luria before him, he let his case histories shore up the theory of the brain as an organ that should be understood holistically, as an organism capable of plasticity and compensation. Although not the inventor of the neurological narrative, Oliver was certainly its culmination. For the coming decades, his legacy will be safe in the hearts and minds of millions of readers.

In conversation, I once brought up his numerous honorary degrees, awards and fellowships — but Oliver was quick to raise his hand to halt me, and said simply that he believed he was a good doctor. He felt that his parents recognized that he had become a careful and perceptive neurologist. Even in his eighties, being a good son was still a defining ambition of his life.