LONDON: The vultures are circling, said the family. Later they withdrew the charge, but who can blame the relatives, visiting the aged patriarch in his hospital bed watched by an ever-expanding encampment of the world’s press. Anyone would recoil at this morbid intrusion of lenses and microphones whose purpose is simply to wait for death.

But the rest of us should not condemn too harshly the journalists preparing to bring us news of the death of Nelson Mandela. They are there not to feed themselves, as vultures do, but to satisfy what will be a global desire to mark a moment that is rare indeed. Just for once, the entire world will be united in mourning. Dissenting voices will be scarce to non-existent. For Mandela is in a category of one, a person known universally and admired, even loved, almost as widely.

That is why the press corps outside Pretoria’s Mediclinic heart hospital is so large, why the US president, on a tour of Africa, is in the unfamiliar position of hoping for a meeting he might not be granted. Truly, no one else on the face of the Earth would get this treatment. There will be an enormous reaction in this country — bigger, I suspect, than many realise — when Queen Elizabeth dies. Hundreds of millions of Catholics the world over will mourn the pope when his time comes. There are other figures with large, international followings. But none has the standing of Mandela, a man whose name alone carries a unique moral weight in any language.

And moral is the word. For what sets Mandela apart is his moral authority, greater than that of any other living individual. This is the source of the intense current interest and wellspring of the grief that will flow when he is gone. Yet, moral authority is a strange, elusive quality. We feel we know it when we see it, but what exactly does it amount to? Who has it and how is it used?

The usual prerequisite is suffering. Harsh to put it so baldly, but most of those who can hush an audience with their presence alone have experienced an ordeal that commands our sympathy and therefore our respect. To light on three disparate examples: Doreen Lawrence lost her son, Stephen, when he was murdered by a racist gang of white youths in London 1993; the Israeli novelist David Grossman lost his son, Uri, when he was killed in combat during the Lebanon war of 2006; James Brady initially lost the use of his legs and much of his speech and cognitive function when he was shot during the attempted assassination of Ronald Reagan in 1981. All three are usually granted a hearing, even if they are not always heeded, in part because of what they have endured.

But pain alone is not sufficient. There are, sad to say, other mothers of murdered teenagers who do not have the standing of Lawrence.

What distinguishes her is the 20-year campaign for justice she has fought since her son’s death. It is in this context that she is listened to, just as Grossman speaks with extra moral authority on Israel’s conflict with its neighbours or Brady on gun control. Each has channelled their experience into a struggle, whether for justice, peace or an end to violence.

What’s more, it is the manner of this struggle that either adds to or reduces a campaigner’s moral authority. Lawrence is said to bristle at the now-clichéd description of her as “dignified”. Yet this is central to the gravitas she exudes. Her calmness, her refusal to rant or rave — even though such outbursts would be wholly understandable — enhance her status. That was clear again this week, as the Guardian revealed that the London Metropolitan police had dispatched undercover spies to smear the Lawrence campaign. Doreen Lawrence’s grace these last two decades ensured this was seen as a violation too far.

If these are the essential ingredients of moral authority it’s not hard to see why Mandela is the uber-example. His suffering, his response to it and his wider campaign for justice are all of a scale and import without parallel.

He was a political prisoner on Robben Island for a barely imaginable 27 years. He was there as the leader and chief symbol of the struggle against apartheid, a cause which, in retrospect if not at the time, has come to be seen as an ultimate, textbook case of good versus evil. That campaign itself became totemic for other struggles around the world, whether against racism or colonial oppression. Across the globe, black people especially saw their own destinies bound up in the fate of Nelson Mandela.

Above all, the way he responded to the brutality he had endured, his generosity towards his captors and his lack of desire for revenge against the wider white minority they had served established him as a kind of paragon. If secular saint is a phrase with any meaning, it applies to Mandela.

Of course there are risks to such canonisation. It can render taboo any criticism of the canonised decisions, including the charge that Mandela left too much of South Africa’s economic inequality untouched. More important, if Mandela was a saint that makes his work a miracle — a one-off event that cannot be replicated. Better to see the victory over apartheid as the fruit of an all too mortal, political struggle by human beings who, Mandela included, had as many flaws and limitations as anyone else.

For all that, moral authority is a precious commodity in politics. It can unlock things that would otherwise be jammed. In long-running conflicts especially, whether in the Middle East or Northern Ireland, it seems only those admired as having struggled for their peoples over many years, perhaps paying a personal price, are trusted to make peace. When Britons lament the state of today’s politics, sighing at the smooth-skinned young men who lead the three largest parties, they are partly grieving the lack of moral authority of those in charge — men who have so little experience of anything outside the political game that they can hardly be blamed for lacking experience of suffering or struggle.

In this, Mandela stands apart, on an entirely different plane. When he is gone, the world will feel a poorer place. No longer will we reassure ourselves that, somewhere, there lives at least one leader who proved capable of true moral greatness. Of course we huddle together waiting for news. Our global village is about to lose its elder.

By arrangement with the Guardian