I had a nice chat recently with Manisha Sinha, who holds the Draper Chair in American History at the University of Connecticut, after I heard about death threats against her following CNN's publication of a piece she wrote comparing Donald Trump to former President Andrew Johnson.

Sinha told me she submitted the commentary after CNN asked, in the wake of Donald Trump's summit with Vladimir Putin in Helsinki, if she could write about any precedent for the way Trump was treating America's allies.

Her piece, which ran July 27, recalled how Johnson, with blatant white supremacist views, was at loggerheads with Congress until he was impeached by the House of Representatives. He cleared an impeachment trial in the Senate by one vote.

"Johnson took his case to the people, Trump style, during the 1866 midterm elections. He played the race card, arguing that giving African-American rights would weaken whites' rights. He called his political opponents traitors, even leading members of his own party," Sinha wrote.

Her commentary, she was told, went viral, becoming the second most downloaded article from CNN that day.

Then the blowback started, including a telephone message on her home answering machine, which she said was racist, vile and misogynist. Most alarming, the caller said he had her address in his GPS and was on his way to her house to kill her.

"This freaked me out a little bit," she recalled during our chat.

Sinha, whose husband was not home at the time, called 911, and police in the Massachusetts town where she lives responded promptly. She said she is puzzled how the caller found her home phone and address, since they are in her husband's name, which is different from hers.

Police found the caller by tracking her phone records.

Sinha asked that I not publish the name of the town where she lives, a request I am honoring.

The police chief of that town told me that Matthew Erickson, 39, of Porter, Texas, has been charged in the county court with threatening to commit a crime and making harassing phone calls. It is unclear whether prosecutors will try to bring him to Massachusetts if he doesn't appear here for his court date, the chief told me.

Sinha, who immigrated to America as a graduate student in 1984, said she believes the incident is evidence of a new incivility that people seem emboldened to use, a "coarseness that seems to come from the top."

It seems to have "unleashed people to be racist in an overt way that wasn't acceptable earlier," she said.

I think she's right.

Sinha profusely thanked the police in her town, whom she said responded promptly and professionally and got to the bottom of the threat.

She said she has traveled often professionally to Texas but is having second thoughts about attending a conference there in the near future where she is scheduled to give a keynote address.

Though the threat was unsettling, she said she won't let it stop her from speaking her mind.

"He was trying to scare me into silence, and I won't let him. That's how you foster authoritarianism," she said.

I was grateful for learning a little more about Andrew Johnson, who some historians say was possibly the country's worst president.

Sinha, in her commentary, drew many interesting parallels to Trump.

"Today, as the party of Trump traffics in nativism, racism, archaic views of women's and gay rights, with political and economic policies lifted from Gilded Age robber barons, it is useful to remember the words of another, far wiser Republican.

"'When it comes to this,' as Abraham Lincoln put it in a famous rebuke to anti-immigrant nativists of the 1850s: 'I should prefer emigrating to some country where they make no pretense of loving liberty — to Russia, for instance, where despotism can be taken pure, and without the base alloy of hypocrisy.'"

This is the opinion of David Collins.

d.collins@theday.com