STELLENBOSCH, SOUTH AFRICA -- There's an aphorism about blacks and whites in South Africa that helps explain why the powers that be eventually abandoned apartheid: "If they don't eat, we don't sleep."

It was coined by Anton Rupert, a legendary Afrikaner entrepreneur who broke the hammerlock that English-speaking whites held for a century over big capital in this country. The Ruperts are one of South Africa's two wealthiest families (the higher-profile Oppenheimers are the other), and through the Rembrandt Group and associated overseas businesses, they control a global empire in tobacco, alcohol, mining and banks.

More than a decade ago, Rupert began prodding his politician friends in the ruling National Party to bury what he called "the stinking corpse of apartheid" -- arguing it was, among other things, bad for business.

Now Rupert's son, Johann, 44, has taken over the business, and he's already positioned himself to play the same role of goad toward the government. But in his time, it will be a different government, and a different message.

Rupert the younger's brief to his country's first black leaders is that they're going to have to run the economy by accepted world norms -- no overspending, no over-inflating, no overborrowing, no overtaxing -- if they expect domestic capital to stay put and foreign capital to land. Without both, he adds, they'll never make a serious dent in the inequities of apartheid, because they won't have the benefit of an incoming economic tide.

"People may have disinvested from here with their hearts, but they'll reinvest with their minds," said Johann Rupert. "Mr. Mandela is going to have to be able to convince a cynical world that a black-run country can make it."

Rupert is relieved that African National Congress leader Nelson Mandela, expected to emerge from this week's elections as the presidential winner, will have the chance. Rupert was raised in this picturesque university town in the wine country just east of Cape Town with a conviction that apartheid was "practically unimplementable ... and morally unjustifiable." As a student at Stellenbosch University in 1970, he raised eyebrows in the insular Afrikaner establishment by helping write a special edition of the college newspaper devoted to a condemnation of apartheid.

He learned the ropes of international banking in New York at Chase Manhattan Bank and Lazard Freres, joined his father's company in 1985, ran the overseas operations for three years, then returned home to take over the whole operation just as the transformation from apartheid to democracy was getting underway.

Rupert has long been a confidante of President Frederik W. de Klerk, and more recently began nurturing a personal relationship with the two top ANC leaders of his generation, Secretary General Cyril Ramaphosa and National Chairman Thabo Mbeki.

Of de Klerk, a golfing buddy, Rupert recalls a lunch the two had shortly after the president began dismantling apartheid in 1990. Rupert was holding forth on some of the pitfalls that lay ahead. De Klerk's mind was elsewhere; his eyes welled with tears. "For the first time in my life I'm free," he told Rupert. "For the first time I can look people in the eye."

Looking ahead to the next government, Rupert said that the ex-political prisoners and exiles have been on a steep learning curve over the past four years -- as has "all of white society... . We're like Siamese twins. We cannot survive without each other."

He counts himself an optimist about the new South Africa, but worries: "If it goes wrong here, then I'm afraid the whole sub-continent is an economic basket case."

If it goes wrong here, Rupert's empire will be damaged but not crushed. One reason his businesses diversified so heavily was to hedge against the very political developments he and his father lobbied for at home. "I have told Mr. Mbeki and Mr. Ramaphosa that their constituents will expect them to steal my constituents' assets -- which is one reason we have taken steps to see that my constituents' assets cannot be nationalized."

Rupert counts that tension in the next government -- between meeting the expectations of the masses without scaring off the resources of the elites -- as a plus. He plans to do his part to keep the pressure on.

"My family has been here since 1662," he said. "We're not going anywhere."