The hypocrite always wears a halo. He walks in the light of his own goodness, encircled by the clarity of illuminated virtue. His dark secret is hidden from sight so he can enjoy popular applause for his undiminished radiance.

So it is with Nobel Prize-winner Gunter Grass, moralist-in-chief of German letters, controller of the German conscience. He demanded that all Germans "come clean" about their past as the only way to atonement. He was the advocate for remembering and taking full responsibility for personal actions. He beat a tin drum to death.

So it was stunning news that now, at the age of 78, he has admitted publicly that he was a Nazi himself, a soldier of the Waffen SS, the special unit that made the Holocaust work. He served in the unit at the end of the war at the age of 17, after, he said, he tried and failed to volunteer for U-boat service. He says he didn't engage in any criminal activity, but he nevertheless hid his Nazi past from the public for six decades.

He urged others to claim their shame, but he waited for a propitious moment to reveal his. Why now? "It weighed on me," he says. But it's hardly a stretch to suggest -- as many Germans do -- that he made his confession shortly before the publication of his autobiography. He may sell more books this way, but once the halo slips, it never quite fits again.

And it was a big halo. Like others of the arrogant intellectual left of European letters (such as the English playwright Harold Pinter, another Nobel Prize-winner), he never lost an opportunity to use his fame and sense of moral superiority to scold America. During the Vietnam War, he compared our "war crimes" to the war crimes of Nazi Germany. He never bothered until now to say that he was a member of the elite Nazi unit commissioned to execute the worst of Holocaust thuggery.

He went out of his way to criticize Konrad Adenauer for his friendship with the United States; he blamed the resurgence of German capitalism, which he loathed, on America. He even invited sympathy from Jews for opposing Ronald Reagan's visit to the cemetery at Bitburg in 1985 because some of his old comrades of the Waffen SS were buried there along with American soldiers. Imagine how eloquent that opposition might have been if he had said then that he, too, was Waffen SS. Instead he only sneered at President Reagan.

He says the first time he confronted racism was in an American prisoner of war camp after the war, watching white soldiers taunt black soldiers. How would he characterize the disappearance of all those Jews when he was growing up? Only in June, in Berlin to address writers at the annual Congress of International PEN, he renewed his criticism of the United States, this time for generating terrorism. "Armed force is used by this superpower to defeat the terrorism it is itself responsible for," he said.

Michael Jurgs, his biographer from whom he also hid his Waffen SS secrets, told the London Sunday Times that the late revelation damages his credibility: "If he had come clean earlier and said he was in the SS at 17, no one would have cared, but now it puts in doubt, from a moral point of view, anything he has ever told us." Lech Walesa, a Nobel Peace Prize medalist, says that Grass should give up his honorary citizenship of the Polish seaport Gdansk, formerly Danzig, where Grass grew up: "If it had been known that he was in the SS, he would never have been given the award." Others demand that he give back his 1999 Nobel Prize for literature.

Naturally Grass is shocked -- shocked -- by the criticism his revelation loosed. "This is definitely an attempt to turn me into a persona non grata." (Well, yes, you might say that.) In his novel "Crabwalk," published in English in 2003, his theme is that Germans were victims of World War II, too. Perhaps he was even then thinking of a defense for himself. In "The Tin Drum" he created Oskar Matzerath, a character who didn't grow after the age of 3, but who beat a drum with great fury to expose the hypocrisy of those who surrounded him. That beat of the drum now exposes him.

"The hypocrite's crime is that he bears false witness against himself," wrote Hannah Arendt. "What makes it so plausible to assume that hypocrisy is the vice of vices is that integrity can indeed exist under the cover of all other vices except this one." Just so.