Simon Wiesenthal weighed 97 pounds when American soldiers rescued him from the Mauthausen concentration camp in May 1945. His body was more fragile than his memory, and he could not expect to survive. Nevertheless, he did, and he was able to hand over a handwritten list of Nazis he knew to have participated in the Holocaust.

 He survived, and so did his mission to pursue the purveyors of unspeakable evil to the ends of the earth. Simon Wiesenthal hunted Nazis like the Nazis hunted Jews. His first motives were rooted in revenge -- and why not? -- but soon motive morphed into mission, the pursuit of justice and the necessity to teach the next generation about what had happened in civilized, oh-so-refined Germany.

  "To young people here, I am the last," he told an interviewer in Vienna a decade ago. "I'm the one who can still speak. After me, it's history."

 History began last week, when Simon Wiesenthal died at the age of 96. His voice is still at last, but his testimony survives. His life spanned decades of changing trends and attitudes toward the study of the Holocaust. He was a major figure, identified with both the sensationalizing and even occasionally trivializing of the Holocaust, but fulfilling what he believed to be his personal obligation to speak for the dead who could not speak for themselves.

 Simon Wiesenthal was the tireless promoter of Holocaust remembrance. The Holocaust Center in Los Angeles, to which he lent his name, has been described, not necessarily pejoratively, as "Half Yeshiva, half Disneyland." Like the Nazi hunter himself, it teaches tolerance with more than a touch of flamboyance.

 His critics accused him of lacking humility, but he is one of the reasons that children study the Holocaust today. He's responsible for documenting facts so grisly, so incredible that the facts at first invited skepticism. He fought both the perpetrators of the Holocaust, the Holocaust deniers and the Jews who wanted to forget rather than to bear witness to evil. "Discovering witnesses is just as important as catching criminals," he wrote in the introduction to "The Sunflower," a short memoir.

 During the Cold War, when governments in the West were more concerned with extracting information from the Nazis about the Communists than in ferreting out the human rats of the concentration camps, more interested in hiring Nazis as spies and scientists than in judging their guilt (Wernher von Braun, the most prominent of the reconstructed German scientists, had been a SS major), he was persistent in his pursuit to take Nazi fugitives to trial. When communism failed, he persuaded countries behind the Iron Curtain to uncover cases against the Nazis buried in police files.

 Laurence Olivier and Ben Kingsley played the Wiesenthal character in the movies, but the real man would never have been taken for James Bond. His flaws were writ large. He was rough, gruff, and sometimes more than a little too puffed up for his own good and the good of his cause. His many sightings of Josef Mengele were sometimes hallucinations or even fabrications. But he contributed information that led to the capture of more than a thousand Nazis, including the unrepentant Adolf Eichmann, who was sent to Israel for a trial and a hangman's rope. He tracked down the Gestapo aide responsible for the arrest of Anne Frank in her hiding place in an attic in Amsterdam.

 Mr. Wiesenthal defended Kurt Waldheim when his Nazi past was finally revealed, and he did not always live up to the moral purity he demanded of others. But he brought important discussions of genocide to the public arena. In "The Sunflower," he writes of how he was asked to offer forgiveness to a Nazi soldier dying in a hospital. He describes his confusion and silence, but he doesn't stop there. He asks contemporary thinkers of various religions to read the story and discuss their own feelings. The book has become a primer for teaching students about the Holocaust without the emotional glibness of the popular culture.

 Student reactions to his book tell much about their understanding of ethics. Berel Lang, a professor of the humanities, used it to teach college students the concept of evil. In "Act and Idea in the Nazi Genocide," he writes how shocked he was at student indifference to Nazi immorality; the students thought the soldier need not ask forgiveness because he was merely a soldier carrying out orders.

 Simon Wiesenthal always said he did what he did so the next generation could learn from his experience, "so that it could not happen again." No small accomplishment. We'll miss him.