Every object in Natick's International Museum of World War IImakes that cataclysm feel more tangible. The vast collection includes a portable British air-raid siren that visitors can activate within seconds; the Enigma machines used by the Nazis to send coded messages; and a terrifying assemblage of Nazi paraphernalia that shows how effectively that regime stoked German nationalism and dehumanized its opponents.

As the memory of World War II recedes, reminders like these may be increasingly necessary. A poll published in April by the Conference on Jewish Material Claims Against Germany found that two-thirds of American millennials don't know what Auschwitz was, and that 52 percent of all Americans incorrectly believe that Adolf Hitler came to power through force.

“I am concerned,” said Kenneth Rendell, the museum’s founder and director. “Every generation keeps forgetting the human stories of the past.”

“People do want to forget war,” he added. “And that's really a good idea — except by forgetting the war, you forget how wars happen.”

In the case of World War II, Rendell says, the prelude to conflict included a political climate which is eerily similarities to today’s.

“You have a large segment of the population that feels they're disenfranchised,” Rendell said. “Nationalism is a huge issue — finding a common enemy that everybody can blame everything on ... The marketing of propaganda, which is enormous: tell lies often enough, just keep repeating them.”

In World War II, that toxic mix took an unimaginable toll: some 60 million people died worldwide, including about 400,000 American troops.

While many veterans of the war have passed away, there are still a handful who remember the conflict firsthand. Among them is 96-year-old Richard Dinning of Natick, who flew B-17 bombers with the Eighth Air Force out of a base in England, primarily over German targets.

Now, Dinning volunteers at the International Museum of World War II every week, sharing his recollections from dozens of bomber missions. Like Rendell, he hears echoes of the conflict growing louder in the present moment.

“I know what being under political stress is,” Dinning said. "I saw Franklin Roosevelt dealing with that.” He added, "How you can be drawn into a battle, even though you don't want to, and how toxic leadership can lead into horrendous battles and wars — I'm reminded of that these days.”

All of which raises a huge question: Can the cautionary lessons from a war fought seven decades ago still shape our decisions today? Or has our collective memory of that period become too remote to have an impact?

Dinning is optimistic. He believes popular interest in World War II is increasing.

“Those who visit this museum, by the time they're exposed to it, and the objects, they begin to have a fairly good appreciation of World War II,” he said.

Rendell is more guarded. For one thing, he says, anyone seeking to impart World War II's lessons today has to strike an extremely delicate balance.

“The horror of all this is really hard to deal with,” he said. “How do you convey as much of that reality as people can deal with? Because really hitting people with all of it, they just shut down.”

And yet, he adds, the alternative is unacceptable.

“The fear is that people won't learn any of the lessons,” Rendell said. “And the lessons are that if you don't appreciate them — if you don't pay any attention — it will all just keep repeating.”