Mahmoud Ahmadinejad got one thing right in his rant at Columbia University. History, he said, can't close the books on the Holocaust because the subject must be approached from different perspectives. That also got him to concede, sort of, what everybody else knows -- that the Holocaust actually happened.

Ahmadinejad in America coincides with the opening of a remarkable new online exhibition at the United States Holocaust Memorial Museum (ushmm.org), which features photographs of Nazi SS officers laughing, flirting and reclining at Auschwitz. These photographs offer a different perspective, true enough, because there aren't many photographs of SS officers at play. Here we see Camp Commandant Hans Hocker, who created the album, smile handsomely into the camera. We see pretty Eva, Angela and Irmgard, "communications specialists" at the camps, enjoying bowls of fresh blueberries. We watch an officer serenading them with an accordion solo.

These photographs document not the banality of evil, but the frivolity of evil. The photographs challenge anew our understanding about how such things can happen among so-called civilized men and women. The devil wears many disguises, and one of them is the appearance of normality, perhaps the most dangerous phenomenon of all, because it's a disguise unto itself.

Museum historian Judith Cohen notes that the photograph of the blueberry feast occurred on a day that 150 new prisoners arrived at the camp, and 33 were selected for work. The rest were sent to gas chambers. The vile odor of burning flesh seems not to have affected the appetites of Eva, Angela and Irmgard. The photographs were chosen because they reveal evil in its deceptive ordinariness: "In their self-image, they were good men, good comrades, even civilized."

That can be said as well of Mahmoud Ahmadinejad. His clowning, his weaving, his bobbing, his smiling on the podium at Columbia University lent an air of normality to his lies and deceitfulness. He looked silly at times, but he didn't frighten anyone with his stage presence. Imagine how the footage with his applause lines will play in the Middle East where they will, no doubt, censor Lee Bollinger's introduction of criticism. The Iranian media reported none of the questions, only that the students gave him a prolonged standing ovation. (An ovation nobody else there saw.)

He had a lot of the Hitler rant in him. For a long time we didn't take Hitler seriously here. He was easily satirized as the "little dictator." In the whole Ahmadinejad controversy over his invitation to Columbia, no remark was more fatuous than Dean John Coatsworth's observation that in defense of free speech, he would have invited Hitler to speak if he were here. His clarification wasn't much better. "[H]ad he come to the United States in 1939, he would have found a country with lots of admirers of his regime. An appearance by Hitler at Columbia," the dean said, "could have led him to appreciate what a great power the U.S. had already become." Some dean's list.

This dean should, in fact, go back to the history classroom. Hitler was anything but a quick learner. He could never see beyond his own prejudices. He thought Britain would capitulate quickly, that the Americans wouldn't fight and that he could defeat the Russians easily.

When William Randolph Hearst interviewed Hitler in Germany in 1934, he went with the hunch that he might do "some good" by meeting him. When the powerful newspaper publisher asked Hitler about the persecution of the Jews, der Fuehrer replied, "There is no persecution of any sort." Hearst was convinced. When someone later asked him about Hitler's anti-Semitism, he replied: "The whole policy . . . of anti-Semitism is such an obvious mistake I am sure that it must soon be abandoned. In fact I think it is already well on the way to abandonment."

When I hear Hitler evoked in contemporary arguments, I return to my dog-eared copy of "Mein Kampf" to reacquaint myself with what that "petty and cruel dictator" had to say in the years before he assumed the power to wreak ruin on so much of the world. He, like Ahmadinejad, was pleased to be vilified. "Any man who is not attacked in the Jewish newspapers, not slandered and vilified, is no decent German and no true National Socialist," he wrote. "The best yardstick for the value of his attitude, for the sincerity of his conviction, and the force of his will is the hostility he receives from the moral enemy of our people."

Ahmadinejad understands how to update such an attitude for the 21st century. We may think he was humiliated by the hostility he confronted at Columbia, but maybe he, like Hitler, understands how to play it out to his advantage against the gullible, the feckless and the frightened.