Columnist

Nothing is ever over. No historic trauma is ever resolved. No historic villain is ever buried, and no historic lessons are permanently learned. Everything and everyone can be revived, and anything can be unlearned — even in the most settled civilizations.

Evidence of this is all around us. After two generations of atonement, an elected German politician — Björn Höcke, speaker of the parliamentary group of the new far-right party Alternative for Germany — wants Germans to stop apologizing for Nazi crimes; he describes the Holocaust memorial in Berlin as a "monument of shame." In China, a government once embarrassed by Maoism is peddling a sanitized version. Last year, 17 million Chinese made pilgrimages to the chairman's home to pay homage to the man whose madness starved far more of his countrymen than that.

In Russia, Stalin has returned. Nearly half the country now views him with sympathy, respect or admiration. Stalin sent millions of Russians — and others — to die in labor camps, deprived millions of food so they starved to death, ordered hundreds of thousands executed, and left his country stunted and impoverished. In his own lifetime, Russians were terrified of him; soon after his death, he was denounced by his successors. When the Soviet Union broke up in 1991, it seemed, briefly, as if the victims of his terror might finally come to terms with his legacy.

Instead, a slow drip of imperialist propaganda, carefully supplied by the Kremlin, has successfully implanted a different memory. Over and over, Vladimir Putin's government reminds Russians that under Stalin, Soviet citizens might have been poor and terrified, but the U.S.S.R. ruled half of Europe. Hagiographic biographies fill Moscow bookstores. An annual parade, complete with soldiers marching in Soviet uniforms and waving Soviet flags, now celebrates Stalin's 1945 victory over Germany.

For a long time, Americans thought they were immune to this sort of thing. But are we really? In the United States of my childhood, there seemed no more settled question than the Civil War. In school I was taught that slavery had been defeated, that Lincoln was a hero and that the remaining wrongs were at least partly righted by the civil rights movement. Even the Old South/"Gone With the Wind" nostalgia had faded and shrunk to a small group of battlefield- ­visiting enthusiasts.

But it never faded away altogether — and now it's back. With a president who looks at white-supremacist marchers and sees "very fine people" and a White House chief of staff who describes Robert E. Lee as an "honorable man" who "gave up his country to fight for his state," we may not be as far as we once thought from a revival of Southern exceptionalism, and even treachery on a broader scale. Roy Moore, Republican candidate for the Senate in Alabama, has said repeatedly that the "law of God" is higher than the law of the Constitution itself.

In each one of these cases, the men who are carefully cultivating defeated ideas from the past think they can then control the impact. Putin wants Stalin to shore up his legitimacy; Xi Jinping hopes Mao can help him stave off opposition; Höcke thinks the shock value of his comments will win him votes. As for Trump and Moore, they think they can win power by appealing to the white- ­supremacist minority and offending the rest. But violent, racist, totalitarian emotions, once unleashed, can go in a lot of unpredictable directions.

In 2014, neo-Stalinist rhetoric helped justify a real Russian military invasion of Ukraine, explained away as a modern battle against "Nazis." Neo-Maoism may be used to justify a new set of political purges. And Moore thinks his ideology gives him the right to overrule the federal judiciary — which is precisely the kind of rationale that led to war in 1861. Imagine Confederate troops as the equivalent of the private, vigilante militias of our era, Confederate politicians as the Roy Moores of their era; it's not that hard to imagine how an argument over gay marriage or a Ten Commandments monument could become the Fort Sumter of our era, especially once Moore is in Washington. It's one thing for a state court judge to defy the federal court. But what happens when a senator does it? And what happens when his party supports him?

Totalitarian ideologies never die, and neither do their appeal, and so their consequences must be carefully re- ­explained for each generation. Supremacist and imperialist ideas make people feel better; mass movements offer confidence and safety. History is always available for rewriting, and wars can always be refought. France's border wars with Germany lasted for centuries; Serbia's modern struggle with Kosovo dates to a battle that took place in 1389. We will be refighting our Civil War 700 years from now, too, so we might as well prepare for it.

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