Florian Maria Georg Christian Graf Henckel von Donnersmarck is an unlikely name for an Oscar winner. It is also an unlikely name for the man who, 16 years after German reunification, at last managed to get both halves of his country talking about the real experiences of those who lived in its now-defunct East.

Mr. Donnersmarck (let’s stick to the shortened version of his name) is a Wessi — a West German born in Cologne, in 1973. When he was working on “The Lives of Others” — recent winner of the Oscar for Best Foreign Language Film — he sent the script to Wolf Biermann, a celebrated East German poet and dissident who later said that he had “flicked through it irritably.” Mr. Biermann explained that he had been “convinced that this novice, this naive upper-class kid who had been graced with being born so late in the West, would never, ever be capable of tackling this sort of GDR material, either politically or artistically.”

But on seeing the film, Mr. Biermann changed his mind. The fictional story involves a young writer, his actress girlfriend, and the Stasi officer who is assigned to watch them. While watching them, he is drawn into their lives. He begins to intervene, even tries to protect them.

The ending isn’t happy, and there are no real heroes in the film: There is nothing terribly attractive about the conformist writer, his collaborationist girlfriend, or even the officer who has a change of heart. Nevertheless, the movie has achieved what nearly two decades of history-writing and secret-file-publishing could not: It got millions of Germans, on both sides of what was the Berlin Wall, to abandon their generalized nostalgia and to focus on the ambiguous and horrible moral choices that people in the East once had to make every day.

Above all, the film made real again the policemen of what had begun to feel like a vanished world. Mr. Biermann writes, “for the first time I saw these phantoms as human beings, right down to their inner contradictions.” He was deeply moved, and so were others. “Sometimes,” he concluded, “a work of art can have more documentary clout than actual documents.”

In this sense, the film is part of an interesting and often ignored phenomenon: Clearly, “The Lives of Others” belongs in that line of filmed dramas that have been powerful enough to force whole nations to discuss painful episodes in their histories. True, not all such path-breaking movies have been as aesthetically accomplished as “The Lives of Others”: Odd though it sounds, one of the first to have that kind of impact was the American miniseries “Roots,” whose 30th anniversary is fast approaching.

In retrospect, many have found fault with that series, not least because its creator, Alex Haley, appears to have plagiarized large chunks of his original book and probably invented some of his genealogical research as well. Still, none of that can lessen the impact of the televised “Roots” — seen in 85% of American households, some 130 million people —which inspired both black and white Americans to interest themselves in their own genealogy and brought the cruelty and horror of slavery into modern American living rooms for the first time.

Interviews conducted on the 25th anniversary of the series contain quotations such as “‘Roots’ has affected my life tremendously” and “It makes me feel like my people have come a long way.” Like it or not, “Roots” mattered: Over the subsequent 30 years, the subject of slavery, previously almost taboo, moved from the periphery to the center of American popular culture, and even academic study, where it firmly remains.

Curiously, another American miniseries, “Holocaust,” had in 1979 a very similar impact in West Germany. Once again, despite claims that it “commercialized” the tragedy — Holocaust survivor Elie Wiesel called it “untrue, offensive and cheap” — the series inspired West Germany to lift its statute of limitations on Nazi-era crimes, and it brought the word “Holocaust” into common usage.

Yet in the deepest sense, all three of these stories are flukes. Why should a miniseries based on a book, which itself contained material from other people’s books, make Americans think differently about slavery? Why should a made-for-TV American movie change the way the German state treats Nazis? And why should a young West German with an aristocratic name have made the first truthful film about the Stasi?

I don’t know: maybe for the same reasons that a Jewish emigre from tsarist Russia wrote “White Christmas.” Despite all the effort put into devising formulas for hit songs, bestselling books and money-making films, the workings of popular culture remain mysterious — just as mysterious as the workings of popular historical memory itself.