Desperate passengers cling to their battered boat, their faces etched with fear: of the bloody war behind them, of the roiling sea beneath them, of the uncertainty that lies ahead.

Leo Goldberger was one of them, once. Watching television footage from Europe, where boats arrive daily carrying ragged people in search of refuge, he can’t help but recall his own flight from his home 73 years ago: The days of hiding from Nazis who would have had him deported and killed. The frantic effort to raise funds to pay off the boatman who would smuggle him and his family out of occupied Denmark and into neutral Sweden. The perilous trip to freedom in a fishing boat’s wet and crowded hold, his stomach churning at the stench of fish, the jolting of waves and the fear of discovery.

“When I see these families,” he said of the modern migrants coming to Europe, “I just see myself in that position. I can so readily imagine their terror, that awful feeling of being on the run.”

More often than not, Goldberger will start to cry at the images on the news. “My heart just goes out to them,” he told the Washington Post. “I know exactly what it’s like.”

When Goldberger and some 7,000 other Danish Jews faced death in concentration camps in 1943, ordinary Danes gave them shelter, money and passage to Sweden, which guaranteed their safe reception. That compassion likely saved Goldberger’s life.

But it seems missing now from Europe’s response to the largest refugee crisis it has seen since World War II, Goldberger said. Denmark has passed controversial laws allowing police to seize valuables from refugees to cover food and housing costs and making it harder for refugees to become permanent residents. Sweden, once seen as Europe’s “humanitarian superpower,” has instituted tougher border controls and slashed benefits in an attempt to deter asylum seekers from coming. And just last Friday, the European Union struck a deal that lets it send virtually all migrants who arrive via the Aegean Sea back to Turkey, turning a country with a checkered human rights record into the region’s refugee camp.

“I think that’s really terrible,” Goldberger said of the most recent E.U. agreement. “Once you’ve escaped in this dreadful manner and you’ve finally found some sanctuary in Greece … to be shipped back must be a terrible, terrible ordeal.”

“I just can’t, I can’t believe that this is the way humans behave,” he continued. “I feel that one has to — even if it means cutting back on one’s own comfort — one has to have an open door to people in need.”

Goldberger recognizes that’s easy for him to say. Speaking from his home in Massachusetts — where he retired after a long career as a psychology researcher at New York University — he is far removed from the crisis currently overwhelming the European continent. The gulf between him and his friends back in Denmark is especially apparent on a day like Tuesday, when the world was reeling from a terror attack that left at least 31 people dead in Brussels.

But still. Imagine if Sweden had turned back Jews during the Holocaust — as so many other countries, including the U.S., had done. What would have happened to him?

It’s too terrible to think about.

Goldberger was 13 years old in 1943, when the German regime that had occupied Denmark for the past three years issued the order for the Jews’ removal. Though he had immigrated to Copenhagen from Czechoslovakia less than a decade before, he considered himself entirely Danish: he sang the national songs, ate rugbrød, was in the Boy Scouts — even now, he still refers to secondary school as “gymnasium.”

But on a night in August, when the Gestapo arrived at the door to his apartment and demanded that Goldberger’s father — a cantor at a prominent Copenhagen synagogue — come with them, the teenage boy was acutely aware of how tenuous their lives in their new country had become.

“My dad came into my bedroom and told me to be quiet. He was not going to open the door,” Goldberger said. “I remember pleading with him to open the door because I was afraid they would break in and shoot everyone.”

Eventually, the officers went away. And the next morning, the Goldbergers woke to the news that 12 prominent Danish Jews had been taken hostage, along with some seven dozen other Danes. If Goldberger’s father had opened the door, he might have been among them.

It soon became clear that the Germans were cracking down. On Sept. 29 — the start of the Jewish new year — Denmark’s 7,800 or so Jews learned at Rosh Hashanah services that the Nazis planned to deport them to concentration camps.

Immediately, almost the entire community went into hiding.

They might have had nowhere to go. But Niels Bohr, the famous Danish physicist, was being spirited out of the country to work on the Manhattan Project at the same time the Jews were forced to flee. When he arrived in Sweden en route to the U.K., Bohr — whose mother was Jewish — told the Swedish government he would not leave until it guaranteed asylum to Denmark’s other Jews. It’s not clear whether Bohr’s demand was what convinced Sweden to open its borders, but on Oct. 2 the declaration came over Swedish radio: If Danish Jews could make it to Sweden, the country would welcome them.

What happened next is known as “the Rescue of the Danish Jews” (Goldberger himself edited a book about it). Christian Danes hid friends and strangers alike in their homes, collected money to cover the cost of their escape and smuggled thousands to Sweden by boat. It was a “rare bright spot in the dark chronicles of the Holocaust” as Goldberger puts it. In the end, Denmark was alone among Nazi-occupied nations in saving almost all of its Jewish population.

Historians have debated what made Denmark different, and Goldberger has his own opinions.

“For one thing, we were Danes,” he said. Many in Denmark deeply resented the Nazi occupation, and helping Jews — who were very well integrated and were viewed as fellow countrymen — was a way to resist.

But Goldberger also believes that there’s compassion at the core of the Danish identity. “They’re very humanitarian in their impulses.”

After hearing the news of the plans for a roundup, the Goldbergers traveled up the coast to a village where they’d once rented a summer home. There, Goldberger and his older brother were sent to ask local fishermen if they could ferry them across the Øresund strait to Sweden, but they were told it was impossible.

So the boys’ father went back into the city to get better information from the resistance movement, and to raise money for the smugglers’ fees he would likely have to pay. On the train, he ran into a Danish woman to whom he’d given a concert a few years earlier. Though she barely knew the Goldbergers, that woman wound up arranging the family’s passage and finding the money to fund it. Yet another stranger who helped save their lives.

On the night they were to leave, Goldberger watched with alarm as his parents raced to collect the few belongings the family could take with them. His mother fretted over the Sabbath candlesticks, a bag of socks that still needed darning. His father rifled through graduation certificates and legal papers.

“Seeing my parents in stress — to me that was worse than anything else,” he recalled. “That’s what made me feel things were truly hopeless.”

Goldberger himself saved little — a favorite flashlight, a small clay sculpture he’d made in an art class.

Then they went out into the darkness and waited in the rain for a signal that it was time to board the boat that would take them to Sweden.

After an excruciatingly long wait, it came: a flash of light off shore. The family of four waded into the icy water — the boatman couldn’t risk docking — then clambered aboard the tiny fishing boat and were quickly ushered into the hold, where about a dozen other people already hid beneath a canvas. The space was cramped and wet and stank of fish, but they were glad for its shelter later, when German officers stopped the boat for an inspection. The refugees held their breath as boots stomped overhead.

Halfway across the strait, the fisherman summoned the refugees from their hiding spot. He couldn’t take them any further; if he entered Swedish waters, his boat would be interned. They would have to wait for a Swedish boat to come across them and carry them to shore.

At last one did.

“In a rather precarious way we went from one boat to the other while the waves were choppy,” Goldberger said. They were now in Swedish territory. But relief didn’t come until they’d reached land. A few hours later, draped in dry clothes and finally fed a warm meal, “We were so relieved,” Goldberger said. “We were so happy.”

The Goldbergers spent two years in Sweden, living in a community of other refugees in Gothenburg on the country’s southwestern coast. Though “we hoped every day that the war would end so we could go home,” Goldberger said he always felt treated well in Sweden.

But the Denmark his family returned to in 1945 was not the home they had left. The country — all of Europe, really — had seen too much horror. Goldberger’s father waited for news of relatives in Czechoslovakia, Austria and Hungary that never came. Most of their extended family had been killed in the death camps.

The family immigrated to Canada, and Goldberger went to McGill University to study psychology. He eventually moved to the U.S. and became a prominent researcher on the psychology of coping — a fitting subject for a survivor, he says. He’s also written and lectured extensively about his life during the Holocaust and his narrow escape.

Never have those experiences felt more salient than in the past year, when more than a million people like him have clambered into boats — “If you can even call those rubber floating things a boat,” he huffed — and crossed a perilous sea in search of a better life, only to find they were unwelcome.

“I have always been extremely grateful for the humanistic effort shown by the Danish people,” he said. “It saddens me to see that things have changed.”

In an interview with Public Radio International that aired in Denmark last month, Goldberger said he tells his Danish friends that they “should be ashamed of themselves” for their treatment of refugees. “They’re doing the absolute minimum.”

“That got a lot of responses,” he told The Washington Post. Irate emails from Danes “who thought I should just be grateful for what they did for me and not make Denmark look bad,” but also rueful emails from friends and strangers who agreed that their country could do better.

“I hate to bad mouth them,” he said of his fellow Danes. “In my heart I really feel like I’m one of them.”

And, he acknowledged, the situations are different. There were just 7,000 or so Danes seeking asylum in Sweden in 1943; more than a million people have arrived in Europe by sea since the start of 2015. The rescue of the Jews was also a matter of protecting Danes against foreigners, whereas Denmark now is being asked to let “outsiders,” in Goldberger’s terms, in. Plus, there are questions of national identity, jobs, social services, security from terrorism — Goldberger heaves a sigh.

“It’s very, very complicated,” he admitted.

And yet, he believes, it’s not. Whatever other considerations there may be, the human one comes first.

“I can’t imagine being a human being without reaching out and helping people in need,” Goldberger said.

Goldberger, who is now 85, will return to Denmark for what may be the last time this August. He hopes to keep telling this story while he’s there — to remind fellow Danes of what they did 73 years ago, remind them of the history they have to live up to.

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