Last week, President Joe Biden strolled the streets of Nantucket with his family and made a noteworthy purchase: a copy of "Democracy Awakening" by Heather Cox Richardson.

Originally intended as a series of short essays addressing common questions such as how the electoral college was formed, Richardson found herself writing about the vulnerability of democracies to authoritarianism.

During an appearance on Boston Public Radio Friday, the Boston College history professor and author cited a saying from Mark Twain: “History doesn't repeat itself, but it often rhymes.” Richardson explained there were moments in history, such as the 1860s and 1920s, when it seemed as if the U.S. democratic system was under attack.

“Each of those times, Americans rose to the occasion and reached back to what I would consider our true history and reclaim democracy. And by our true history, they reached back to the idea that we should all be treated equally before the law and have a right to a say in our government.”

Now, she witnesses democratic stress following the presidency ofDonald Trump and his immune figure. She examines him as a “strongman,” a concept based on the 1951 book by Eric Hoffer, “The True Believer.”

“He said 'Let's stop worrying about the Hitlers and the Mussolinis of the world, because every generation has Hitlers and Mussolinis. What we really need to figure out is why people follow those strong men,'” Richardson explained.

She said the majority of support for figures like Trump comes from people who feel neglected, who can become supporters so long as they are convinced to hate someone.

“Once you get that system [of a strongman] underway, it's got a natural momentum of its own, leading us in this moment to Trump calling his Democratic opponents vermin,” she said.

Richardson argues that the rise of authoritarianism in the United States “follows basic patterns which the people in the United States who don't come from other countries are not necessarily attuned to. … I start the book with the idea that Americans seem to think that authoritarianism comes with goose-stepping soldiers and tanks. And the truth is that authoritarianism usually arrives through the ballot box.”

Richardson's Substack, "Letters from an American," further explores these topics. With her large audience, she feels a heavy responsibility knowing her words have influence.

“I do think I have a little bit of an advantage, perhaps over some who are in the field of journalism, and that's that I've been a teacher for 30 years. So I am accustomed to understanding that what I say has enormous weight,” she said.