The media, the chattering classes — even the GOP establishment itself — are quaking at the prospect of Donald Trump becoming the U.S. Republican presidential nominee. What, if anything, does history have to offer on the subject?

According to world-renowned Canadian historian Margaret MacMillan, maybe a fair bit.

MacMillan, who delivered last year's CBC Massey Lectures, believes there's a widespread appetite to extract whatever lessons history can offer us.

Donald Trump and Margaret Thatcher

Margaret MacMillan looks at the hubris of Margaret Thatcher, the British prime minister who seemed politically invincible in her own day, and the apparent invincibility of Donald Trump. (Associated Press)

MacMillan, who is a professor of international history at St. Antony's College at the University of Oxford, is also the presenter of a TV special and web series inspired by the Masseys called The Art of Leading.

In it, she sounds this cautionary note: "Exercising power can do strange things to people. You can become convinced that you're irreplaceable. You can become convinced that you're always right. And I think the danger is the longer you stay in power the more likely that is to happen."

In a clip from The Art of Leading, included at the top of this page, MacMillan looks at the hubris of Margaret Thatcher, the British prime minister from 1979 to 1990 who seemed politically invincible in her own day, and the apparent invincibility of the mop-top Trump.

Margaret MacMillan on stage1:04

A persistent worry for many is Trump's continued popularity. "In the polls, he is doing well," says MacMillan. "And he doesn't seem to pay any penalties for saying dreadful things or making awful mistakes or contradicting himself. It just seems to boost him again." 

History's People

Margaret MacMillan's lectures, entitled History’s People, are published by House of Anansi Press. (House of Anansi Press)

But everlasting righteousness is not a trait inherent in mere mortals, no matter how strong their political momentum may be.

"No one is always right," MacMillan says. "The only person, if you're a religious person, who's always right is God. And if you make the mistake of thinking that you, like God, are always right, and that you, like God, always know everything, then it seems to me you're riding for a fall."

The Art of Leading airs on CBC-TV at 2 p.m. ET on March 27. MacMillan's 2015 CBC Massey Lectures can be heard from March 28 to April 1 on CBC Radio One's Ideas

Her lectures, entitled History's People, are published by House of Anansi Press.