Assessing the legacies of national leaders is not an exact science.
Politicians and their ideas are no less subject to the vagaries of fashion than pop songs or cuts of trouser.
The issue or idea that seemed important at the time seems frivolous or ridiculous.
A few decades on, the prime minister or president condemned as a buffoon and a charlatan by one generation of pundits may be admired as a sagacious statesperson by the next.
Where US Presidents are concerned, such turbulence is especially severe.
Given that a minor industry exists in ranking occupants of the White House against each other, the fluctuations can be somewhat giddying.
The first such survey of scholars for Life magazine in 1948 awarded predictably high marks to Abraham Lincoln, George Washington and Franklin Roosevelt.
But damned Ulysses Grant and Warren Harding as the two most abject failures.
A more recent poll of boffin by the Presidential Greatness Project garlanded the same top three, but had Grant in 17th, only narrowly behind Woodrow Wilson and Ronald Reagan.
And Harding, at least out of the relegation spots, last by some distance in that one.
Incidentally, Donald Trump, who American voters have nevertheless awarded the opportunity to make up some of those places beginning January 20th.
It is therefore as good a time as any to consider how a presidential legacy is assessed and maintained.
What makes a president great?
Why do our views change over time?
And how do you uphold the legacy of someone who not only failed to even become president, but lost 49 states in the attempt?
This is the Foreign Desk.
He really put the south on the map in a different way.
He put a liberal perspective, a very open to the country, which is very different from what people thought Southerners from the Deep south were.
Andrew Jackson was in certain respects America's first populist president.
If we think about the kind of person that Bernie Sanders has been and his emphasis, his willingness to talk about poverty, I mean, that was McGovern.