Nelson Mandela comes to the United States -- in triumph, in dignity and, characteristically, in modesty. It's hard offhand to think of another figure who has so captured the public imagination and who, moreover, has lived up to advance billing. During the 27 years Mandela spent in prison, the Mandela legend grew and grew, and in freedom it grew some more. The myth of Mandela is exceeded only by the reality.

But Winnie Mandela also comes to the United States. She's a more problematic individual -- linked to the murder of a 14-year-old antiapartheid activist, Stompie Seipei. A court found that he was killed by a member of Mrs. Mandela's security detail, the Mandela United Football Club, and allegedly beaten beforehand by Winnie Mandela herself. For this and other reasons -- her grandiose life style, for instance -- Mrs. Mandela was for a time shunned by other black leaders.

How shall we deal with Winnie Mandela? For most people, the answer seems clear. She's ignored. Specifically, her involvement in the Seipei affair is either not mentioned or rationalized -- excused because of her imprisonment, including 491 days of solitary confinement in the early 1970s. Others might cite her husband's long imprisonment -- an ordeal for him, but for her as well. But many South African black leaders are not so charitable. To them, Mrs. Mandela is nothing less than a loose cannon.

To my mind, Winnie Mandela is more than just the wife of Nelson Mandela. She is, in a way, evocative of the ethnocentric way many Americans see South Africa. To many of us, it's the functional equivalent of the old American South -- racist, rigidly segregated and morally abhorrent. Therefore, the problem is not Winnie Mandela but the system she has fought for a lifetime.

But to visit South Africa is also to confront the reality of the place, and Mrs. Mandela is a piece of that reality. At the moment, for instance, black South Africans are killing other black South Africans in numbers that exceed Lebanon and Northern Ireland combined -- some 3,500 since 1987. Most of the violence is taking place within the Zulu tribe, but some has taken the form of the ghastly "necklacing" -- the burning of informers and others. Nelson Mandela and the leadership of the African National Congress were appalled. Not so Winnie Mandela. "With our matchboxes and necklaces, we shall liberate" South Africa, she said. The ANC told her to shut up.

Americans seem unwilling to deal with such complexities. We tend to view other countries through our own cultural or historical prism. For blacks, that prism has been -- and remains -- racism. Thus, when white South Africans (or blacks, for that matter) express anxiety about the future, their worries are dismissed as racist. Even when some people express doubts about economic sanctions, they are asked which side they are on -- that of black South Africans or white racists? Never mind that some South African blacks also oppose sanctions.

The question of which Mandela represents the future of South Africa is not an academic one. We sometimes mistakenly consider a single person characteristic of an entire country. Washington was once dazzled by the shah of Iran, a most reasonable fellow. He was replaced, though, by Khomeini, a most unreasonable fellow. We were charmed by Corazon Aquino. Filipinos seems less enamored -- and Mrs. Aquino is collecting coup attempts the way Imelda Marcos collected shoes.

The future course of South Africa may well have been set by government-supported violence that once enforced the apartheid system. Years of racial isolation, of repression and of poverty have made many black South Africans hard and bitter. It may be understandable that people accustomed to violence and so often the target of it may turn to it themselves, but it is no less tragic.

The United States, especially the black community, was instrumental in isolating South Africa, pressuring it to change its system -- telling it over and over again that its racism was unacceptable. For those same people to ignore Winnie Mandela and what she stands for sends a clear but ominous signal. In the first place it means that whites will be held accountable for violence, but blacks won't. Second, it undercuts the very conciliation efforts of Nelson Mandela and other ANC leaders. Nelson Mandela's plea to stop the killing among blacks has been ignored.

So what shall we do about Winnie Mandela? The answer so far has been to ignore her activities and concentrate instead on her husband. That's the understandable, even polite, thing to do. But the question raised by her presence here sooner or later has to be addressed. Ultimately, the very people who welcome one Mandela may have to repudiate the other.