By Peter Biles
BBC News, South Africa
No matter how often I see Nelson Mandela, it is always a special moment that makes me feel privileged to live and work in South Africa.
Nelson Mandela is celebrating his 90th birthday on 18 July
This week, he came to the French School in Johannesburg for a birthday function arranged by one of his charities, the Nelson Mandela Children's Fund.
The children all wore T-shirts in honour of the man they call "The Children's Champion".
Mandela arrived in one of his trademark tops, a flamboyant gold and white patterned shirt, buttoned at the collar.
He sat in a red armchair, in his element, surrounded by hundreds of children.
As he listened to the speeches, he looked slowly around the audience closest to him, then nodded and smiled in what seemed like a host of personal acknowledgements.
All of us felt we were being singled out by the old man with the white hair.
An hour later, Nelson Mandela made his way outside, into the grounds of the school to cut a huge birthday cake.
Alongside him was his wife, Graca Machel, the woman he married 10 years ago on his 80th birthday.
There was a frenzy of excitement among adults and children alike as they pushed forward, all trying to capture a photograph.
As I watched Nelson Mandela preparing for his 90th birthday, I thought about those long years he spent in prison, at the mercy of the apartheid state.
I have an old "Who's Who of South Africa" in my bookcase, dating back to 1986.
Mandela's entry is notable for the blank white square alongside his name.
Reaction to the freeing of Nelson Mandela in 1990 was mixed
"Photograph prohibited by South African law," it says.
No-one knew what Nelson Mandela looked like then.
He had been a prisoner for more than 20 years at that stage, and only a handful of people ever got to visit him.
One of them was Helen Suzman, the veteran liberal politician who for six years was the only female MP in South Africa, and the sole voice of serious opposition in parliament.
When I met her this week, she told me about her first encounter with Nelson Mandela in 1967.
She saw him in the prison on Robben Island. And what struck her most forcibly was that this was a man who was "a real leader", someone with an unmistakeable air of authority.
Helen Suzman campaigned hard to improve the conditions for Mandela and the other political prisoners, but seven years were to pass before the authorities allowed her back to the island to see him again.
When Nelson Mandela was eventually released in February 1990, there were mixed emotions in South Africa.
Joy, of course, but also concern that after 27 years behind bars he might, as Archbishop Desmond Tutu put it, emerge as "a man with feet of clay".
And many white South Africans, who had long been fed a diet of state propaganda, were even more apprehensive.
They had been led to believe that Mandela was a dangerous terrorist who was intent on turning South Africa into a communist state.
It was not long of course, before Mandela laid all the anxieties to rest.
Two weeks after his release from prison, I was on the tarmac at Lusaka Airport in Zambia as a red carpet was rolled out and troupes of dancers gathered to welcome Nelson Mandela on his first journey out of South Africa in nearly three decades.
His African National Congress was still in exile in 1990 and this was a momentous reunion.
Mandela was met off the small twin-engine plane by Zambia's president, Kenneth Kaunda who, being a man prone to shows of public emotion, always clasped a large white handkerchief.
Then Mandela embraced his old comrades. Among them was Joe Slovo, a giant of the liberation struggle.
A little while later I asked Slovo what Mandela had first said to him after the 27-year-long interruption to their friendship.
"He just asked me how my three daughters were," said Slovo.
In recent years I have watched Mandela working his magic on everyone from Kofi Annan to the Manchester United football team.
Like anyone approaching the age of 90, he is taking things a lot easier now.
The public engagements are few and far between, and sadly, the days when he would speak freely and off-the-cuff are pretty much over.
Mandela's loyal assistant, Zelda La Grange, protects him doggedly.
There is no doubting the love that South Africans have for Madiba, to use his clan name.
The other day, I took a sounding from my hairdresser, a 20-something white Afrikaans-speaker, who is almost too young to remember Mandela's release from prison.
"Oh, he's my icon," she replied, without hesitation.
The former prisoner and president has risen far above the politics of this once troubled nation. And everyone just wants a tiny slice of this extraordinary man.
From Our Own Correspondent is broadcast on a Saturday at 11.30 BST, on BBC Radio 4. Please check the programme schedules for World Service transmission times.