BERLIN — THE trial of Oskar Gröning, the 93-year-old “accountant of Auschwitz,” began last week in the German city of Lüneburg. Mr. Gröning is charged with complicity in the murder of at least 300,000 people. At least once during the summer of 1944, according to his accusers, when thousands of Hungarian Jews arrived by cattle car at Auschwitz-Birkenau, he stood at the exit ramp, watching as the passengers were divided into those to be put into forced labor and those to be killed instantly.

The trial has gained widespread attention in Germany and around the world, and not only because Mr. Gröning expressed regret for his actions. A number of survivors of Auschwitz are in attendance, and their statements have given the proceedings an added poignancy. It is one of the last chances we will have to hear the victims and seek justice from someone who actually participated in the Holocaust. The rapid disappearance of the “Zeitzeugen,” the contemporary witnesses — both survivors and perpetrators — will change how we Germans think about ourselves. Especially the perpetrators; in a bizarre way, we will miss them when they’re gone.

Since the end of the Nazi era, Germany has made “never again” a core part of its national identity. Deterrence, as an educational concept, has shaped how we commemorate our past, structure our politics and teach our children.

It is not enough to teach good liberal values. All that Humboldt and Kant failed to inoculate Germany from the virus of Nazism. Why should it now? Nor is history sufficient, by itself. The numbers of those killed in Auschwitz-Birkenau are horrifying, but abstract.