The icon is a very old man now. His hair is white, his body frail.

Visitors say Nelson Mandela leans heavily on a cane when he walks into his study.

He slips off his shoes, lowers himself into a stiff-backed chair and lifts each leg onto a cushioned stool.

His wife, Graca Machel, adjusts his feet “so they’re symmetrical, and gives him a peck,” says George Bizos, his old friend and lawyer.

To Mandela’s left is a small table piled with newspapers in English and Afrikaans, the language of the whites who imprisoned him for 27 years.

Family and old comrades sit to his right, where his hearing is better.

His memory has weakened, but he still loves to reminisce, bringing out oft-told stories “like polished stones,” as one visitor put it.

“There’s a quietness about him,” said Barbara Masekela, his chief of staff after his release from prison in 1990. “I find myself trying to amuse him, and I feel joyous when he breaks out in laughter.”

Mandela, perhaps the world’s most beloved statesman and a natural showman, has repeatedly announced his retirement from public life only to appear at a pop concert in his honour or a political rally.

But recently, as he cancelled engagements, rumours that he was gravely ill swirled so persistently that his foundation released a statement saying he was “as well as anyone can expect of someone who is 91 years old.”

Yet even as Mandela fades from view, he retains a vital place in the public consciousness here.

To many, he is still the ideal of a leader — warm, magnanimous, willing to own up to his failings — against which his political successors are measured and often found wanting.

He is the founding father whose values continue to shape the nation.

“It’s the idea of Nelson Mandela that remains the glue that binds South Africa together,” said Mondli Makhanya, editor in chief of The Sunday Times. “The older he grows, the more fragile he becomes, the closer the inevitable, we all fear that moment. There’s the love of the man, but there’s also the question: Who will bind us?”

There is a yearning for the exhilarating days when South Africa peacefully ended white racist rule, and a desire to understand the imperfect, bighearted man who embodied that moment.

Because of this, various historians and journalists are at work on a new round of books about Mandela.

The Nelson Mandela Foundation agreed last month to sell the rights to a book, Conversations With Myself, to publishers in some 20 countries, based on material from Mandela’s personal papers — jottings on envelopes, journals, desk calendars, drafts of intimate letters to relatives written in prison and documents from his years as South Africa’s first democratically chosen black president.

“He was and still is an obsessive record-keeper,” said Verne Harris, who has been Mandela’s archivist since 2004 and will knit together the excerpts with Tim Couzens, a biographer. “The oldest records we have in that collection are his Methodist Church membership cards, the earliest one dated 1929. So he was 11 years old then.”

There are telling nuggets in unexpected places.

In his prison years, the authorities gave him a South Africa tourist desk calendar each year.

He typically recorded facts in it — his blood pressure, or whom he met that day — but occasionally he noted a dream, like one in which his daughter Zindzi, whom he was not allowed to see from when she was three years old until she was 15, “asks me to kiss her and remarks that I am not warm enough.”

The book will also draw on 71 hours of taped conversations that Mandela had with Richard Stengel, who collaborated with him on his autobiography, Long Walk to Freedom, and Ahmed Kathrada, Mandela’s prison comrade.

“One of the amazing, uncanny things was his memory,” said Stengel, Time magazine’s managing editor. “It was like he was watching a movie of his life and then narrating it. He would do voices of his father, of his teachers, of his prison guard.”

Eventually, after a team at the foundation has catalogued the entire archive, the foundation plans to digitise it and put it on the Internet. The vast bulk of it is not yet public.

Historians say they are not expecting major surprises about Mandela’s generally well-known views, but hope to find rare glimpses of the man.

Mandela is looked after by his wife, Graca Machel, 64, the widow of a former president of Mozambique and a humanitarian activist.

“They behave like young lovers,” Bizos said. “They hold hands.”

Here in Johannesburg, it is not unusual for residents of his neighbourhood, Houghton, to gossip about how he is doing.

Harris, seeking to douse rumours that Mandela is deteriorating, said he was still healthy but tired of small talk with strangers.

“He can reminisce at great length about things that happened years and years ago,” Harris said. “But you know what old age is like. Short-term memory starts to malfunction, and you have bad days.”

His oldest friends, stalwarts of the anti-apartheid struggle, still visit.

Bizos, who went to law school with Mandela in the 1940s, said Machel worried that Mandela would be alone when she was out of town, and eat too little without company.

So from time to time, Bizos gets a call from their housekeeper to come for lunch.

Mandela sits at the head of a large table, with Bizos to his right.

They relish their favourite dish — oxtail in a rich sauce — and talk about old times.

Mandela tells how he walked into a law school class and sat next to a white fellow with big ears, who promptly changed seats to avoid sitting next to a black man.

Mandela had wanted to invite the man to their 50th reunion at the University of the Witwatersrand in 1999, but the man had already died.

“He repeats it from time to time,” Bizos said. “He regrets he did not have the opportunity to meet him. He would have said to him, ‘Do you remember what happened? But please don’t worry. I forgive you.’”

Like a grown child for whom each goodbye to an aged parent feels as if it may be the last, South Africa seems to be preparing itself for the final farewell to its epic hero.

And Mandela seems to have readied himself, poking fun at his infirmity.

Harris recounted a joke he had heard Mandela tell and retell.

“When I die, I am going to get up to the gates of heaven, and they’re going to say to me, ‘Who are you?’” Mandela says. “And I will say, ‘l am Madiba,’” he said, referring to his clan name.

“And they’ll say, ‘But where do you come from?’ And I’ll say, ‘South Africa.’ And they’ll say, ‘Oh, that Madiba. You’ve come to the wrong gates. You see the ones down there that are very warm? That’s where you have to go.’”

Mandela’s wish is to be buried alongside his ancestors in Qunu, on the eastern Cape, where he spent the happiest years of his boyhood.

In his autobiography, he describes it as a place of small, beehive-shaped huts with grass roofs.

“It was in the fields,” he wrote, “that I learned how to knock birds out of the sky with a slingshot, to gather wild honey and fruits and edible roots, to drink warm, sweet milk from the udder of a cow, to swim in the clear, cold streams, and to catch fish with twine and sharpened bits of wire.”

NY Times