Ban Ki-moon is not the best secretary-general the United Nations ever had, but he has grasped the essential nature of his job.
The UN is an organisation made up of sovereign states and their highest priority is the preservation of their own privileges.
It is the trade union of the sovereign states of the world and Mr Ban is their shop steward.
Which is why he said what he did last weekend.
Speaking just before the African Union summit opened in Addis Ababa, the UN secretary-general declared that both the UN and the AU had a big responsibility "to maintain peace in Sudan and make unity attractive".
It is not immediately obvious that peace and unity are compatible in Sudan, where civil war killed about two million people and created four million refugees between 1983 and 2005, but Mr Ban was in no doubt about it.
The fighting in Sudan ended in 2005 when the northern-based government and the southern-based rebels signed a Comprehensive Peace Agreement that created a unity government in Khartoum and a separate regional government in the south, and promised the southerners a referendum on secession next year.
That promise was what stopped the fighting and despite many crises and clashes it has held for five years.
Not only that, but the dictator in Khartoum, President (and ex-general) Omar al-Bashir, recently declared yet again that he will respect a southern decision to secede.
"The National Congress Party favours unity," he said in December. "But if the result of the referendum is separation, then we in the NCP will be the first to take note of this decision and to support it."
So here is this Korean bureaucrat, Ban Ki-moon, urging African countries to back the unity campaign of the regime in Khartoum - a regime whose leader, President Bashir, is under indictment by the International Criminal Court for the massacres carried out by government-backed militias in Darfur.
What's more, Mr Ban is ultimately in control of the UN troops who are stationed in Sudan to guarantee the peace agreement.
Yet he clearly said which side he backed in the referendum: "We'll work hard to avoid a possible secession".
Who does this guy think he is? He knows.
He is the shop steward of the Federation of Sovereign States and Allied Trades (also known as the United Nations) and his job is to preserve the rights and privileges of its members.
Their most important right, of course, is to keep control of all their territory forever, regardless of the views of the local people.
The African Union is particularly devoted to preserving the unity of all its members, because Africa's borders are particularly arbitrary and irrational.
If any of the disparate ethnic groups that are trapped together in country A were allowed to secede, then the demand for similar secessions in countries B to Z would become irresistible, or so the African orthodoxy has it.
"No secessions" was the paramount rule of the old Organisation of African Unity and it survived unbroken until Eritrea got its independence from Ethiopia in 1993.
That was not an encouraging precedent, since Eritrea and Ethiopia soon ended up at war with each other, and no further secessions have been recognised since then.
But there is another way to look at this and that is to count the cost of all the wars that have been fought in Africa to prevent secessions.
From the Biafran war in Nigeria in the 1960s down through the various secessionist movements in the Congo and Ethiopia and on to the breakaway movements in Sudan's south and west (Darfur) today, at least 10 million Africans have been killed.
For what? Nobody, except some ruling elites would be worse off if the secessions had been allowed to succeed.
The Nigerian elite would have somewhat less money to put into its overseas bank accounts, since the oil money would have stayed in the southeast and a new Biafran ruling elite would have bigger Swiss accounts.
Maybe what remained of Nigeria would have split into a Muslim north and a Yoruba-speaking Christian southwest, since without Biafra the country would have become a Muslim-majority state.
So what? Maybe everybody would have been happier that way.
Most people will probably be happier if Sudan does split in the referendum planned for January 2011.
Those in the Muslim, Arabic-speaking north would have co-existed peacefully with the various Christian and animist ethnic groups of the south if they had been left to their own devices.
However, the northern ruling elite imposed Islamic law to consolidate its power and the southern elites responded with appeals to ethnic solidarity.
If the south leaves next year, it will take most of the oil with it. That is why the northern elite fought so hard to save national unity . . .
But the oil still has to go out to the sea through northern territory, so the revenue will still be shared.
After two decades of killing, Sudan is broken and the best solution is independence for the south.
Unless Ban Ki-moon and his trade union get their way, in which case the war will resume.
Gwynne Dyer is a London-based independent journalist.