Anne Applebaum is a Washington Post columnist.

Twenty years ago, I visited South Africa and got lost. I set out from my hotel in Durban in search of a small black college where some leaders of the African National Congress (ANC) party were meeting before the country’s first post-apartheid elections. I drove around Durban’s white suburbs for hours, looking for a building that was not on my map because, technically, it was not in Durban. It was in KwaZulu, one of the black “homelands” that existed alongside but legally separate from the white neighborhoods. When I stopped for directions, nobody I asked had ever heard of the college, even though it was only a few miles away.

South Africa is so different today as to be unrecognizable. Living restrictions are gone, neighborhoods that were once all white are integrated, the homelands are no more. At a Johannesburg mall, black and white shoppers buy sneakers and eat frozen yogurt together without caring that such a thing was once unthinkable. In newly prosperous Soweto, Nelson Mandela’s house is a museum crowded with black and white tourists. Outside Pretoria, a black guide showed me around the less-crowded “Great Trek” monument, built in 1937 as a shrine to white Afrikaner supremacy. “It is a difficult history,” he agreed. “But we have to know all of it.”...