Former President Barack Obama says Americans must be vigilant in their defense of democracy or risk following the path of Nazi Germany in the 1930s.

At a speech earlier this week, the former president told the Economic Club of Chicago that “things can fall apart fairly quickly” if Americans don’t “tend to this garden of democracy.”

“We get complacent and assume that things continue as they have been, just automatically, and they don’t,” Obama continued.

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Pointing to Hitler’s rise to power in Germany, he said: “You have to tend to this garden of democracy — otherwise, things can fall apart fairly quickly. And we’ve seen societies where that happens,” he added, referring to the late 1920 and 1930s.

“Now, presume there was a ballroom here in Vienna in the late 1920s or 30s that looked pretty sophisticated and seemed as if it, filled with the music and art and literature and science that was emerging, would continue into perpetuity,” Obama said.

“And then 60 million people died. An entire world was plunged into chaos,” he concluded, offering simple advice: “So you’ve got to pay attention and vote.”

Obama also defended the media. He said the press “often drove me nuts” but that he understood that a free press was vital to democracy.