From time to time I am reminded of all that Europe lost. It can happen in the most unlikely places, like in San Diego for example.

I was sitting the other day with a friend named Bonnie Richins. She told me that, as children, she and her sister were not allowed to wear striped clothes. They reminded her father, Kurt Lorig, of the pajama-like attire the Nazis forced him to wear in Auschwitz.

Kurt was born a German Jew. Unlike most of his family, he survived the Holocaust, became an American, settled in California and built a business in outdoor furniture. He always drove an American car. In the 1950s he would sometimes amuse himself by trying to force German-made Volkswagen Beetles off the road — or almost.

Shortly after he arrived in the United States, Kurt and his girlfriend eloped to Tijuana. The marriage lasted over 50 years. It was punctuated by a separation. During that time Bonnie’s sister, who was bipolar, died on an L.A. freeway. She had pulled over. Her car was still running. She had wandered into the road.

Like many survivors, Kurt did not speak of what had happened in Europe. What had happened was unspeakable. Auschwitz left no words. It overwhelmed the lexicon of the hitherto.

About 36.5 million Europeans died between 1939 and 1945 from war-related causes, over half of them civilians, some six million of them Jews targeted for extermination by the Third Reich and its accomplices from Vichy to Vilnius. As the late Tony Judt observed in “Postwar,” his magisterial history of Europe since 1945, “No other conflict in recorded history killed so many people in so short a time.”

This was the culmination of the 31-year European suicide that began in 1914. Europe lay in ruins. Millions of stunned refugees wandered among the charred vestiges of what had once been called European civilization. Borders were redrawn, whole populations moved like pawns on some diabolical chessboard, Germany cut in two and, at Yalta, Europe east of the Elbe ceded to Stalin’s totalitarian empire.

Europe had lost not only Kurt. It had lost almost everything. It had lost half itself. It had lost much of the mingling of which it was composed. In Germany at the end of the war, 21,450 of the country’s 600,000 Jews remained. This, for a long time, Europe chose not to recall in any detail. It had also lost its memory.

America, which had helped liberate Europe, inherited not only wounded young souls like Kurt who would live out their lives without ever quite being able to explain how they got to where they were. It had inherited the earth.

At this moment of European crisis, of European uncertainty, of potential European fracture, I always try to recall the road traveled since 1945. It is the least of considerations toward those 36.5 million dead of seven decades ago. It is the only way I know to assess the European achievement — the vast accumulation of interlinking accords the French call the European acquis — at its true value.

It also seems to me impossible to consider any of Europe’s current dilemmas — from the uses of German power, to Vladimir Putin’s new threat, to the fate of desperate refugees, to the survival of Europe’s common currency — without this reference point.

There is the euro. Then there is war and peace and that other kind of debt.

In “Reunion,” Fred Uhlman’s extraordinary novella exploring the Jewish loss of Germany, the teenage protagonist Hans Schwarz muses on his condition as Hitler rises to power: “All I knew then was that this was my country, my home, without a beginning and without an end, and that to be Jewish was fundamentally no more significant than to be born with dark hair and not with red. Foremost we were Swabians, then Germans and then Jews. How else could I feel?” His father, a doctor twice wounded in World War I, is convinced the rise of the Nazis “is a temporary illness.” The proud physician lambasts a Zionist who is trying to raise funds for a modern state of Israel: “Do you really believe the compatriots of Goethe and Schiller, Kant and Beethoven will fall for this rubbish? How dare you insult the memory of twelve thousand Jews who died for our country? Für unsere Heimat?”

This book, with one of literature’s most shattering final sentences, is a reminder of the German Jewish devotion to the Heimat that was as fervent as it proved misplaced. Jews departed or went to their deaths. A few, like Kurt Lurig, came back from the camps.

In 2005, a decade after President Jacques Chirac broke a long taboo by acknowledging France’s role in the extermination of European Jews, Jean-Pierre Raffarin, then the French prime minister, declared on a visit to Israel that France was thereby “bound forever by the debt she has incurred.”

Germany’s debt to Europe can never be repaid. It is the real and deepest one.