On Monday 7 August 1962, Arthur Schlesinger, liberal historian and adviser to President John F Kennedy, had lunch at the White House with a friend of his, Harvard historian Frank Freidel. Naturally enough, the pair stopped off in the Oval Office for Freidel to be introduced to the president.

Among the things discussed was an article written by Schlessinger’s father, also a very accomplished historian, and published the previous month in The New York Times Magazine. In the piece, Schlessinger Sr published the results of a poll of 75 leading historians asked to name the country’s most successful presidents.

Schlesinger Jr recorded the conversation in a letter to his father a few days later:

JFK again expressed his surprise over [Woodrow] Wilson’s high rating, and also over Theodore Roosevelt’s. In discussing Wilson, JFK argued that his Mexican policy was a disaster for which we still have not been forgiven; that he had messed up the League [of Nations] fight; and that, though he was right to bring us into the war, he did so for the wrong reasons. On the subject of unrestricted submarine warfare, JFK said, he thought the Germans had good reason to object. As for TR, JFK said that he talked a lot but didn’t do very much. He could not see why TR rated above [James K] Polk or [Harry] Truman.

And here’s what Schlessinger took from Kennedy’s analysis:

What is most interesting is that his criterion is obviously that of concrete achievement rather than politics education. People who educate the nation, without achieving all their goals, like Wilson and TR, evidently seem to him to rate under people with a record of practical accomplishment, like Polk and Truman, even if they do little to transform the intellectual climate of the nation.

At the time, Kennedy’s comments would, I suspect, have been moderately interesting, but not particularly noteworthy.

But looking back on the Kennedy administration now, his thoughts are fascinating.

Because in many ways Kennedy is remembered as the type of president he admired less — more Wilson than FDR. There were certainly concrete achievements in foreign policy, though the record there is mixed: the Pay of Bigs, Cuban missile crisis, Vietnam.

Yet on the domestic policy front popular history remembers very little of the nearly three years of the Kennedy presidency. It’s for this reason, I think, that it often seems like Kennedy was President for a shorter period than he actually was (he was in office for three-quarters of a term).

Nearly all the important social legislation of the 1960s was passed during Kennedy’s successor’s presidency: that of Lyndon B Johnson.

It is true that Johnson skillfully used the feeling of national solidarity after Kennedy’s death to persuade (or really force) congress to pass the two bills the president had been pushing before his death, on civil rights and tax cuts. So I suppose those victories can in part be attributed to Kennedy. But while the context was important, it was Johnson’s own political savvy which meant he actually achieved the passage not only of these two bills but of the rest of his social programme in his War on Poverty.

So there is a good case to be made that Johnson actually achieved much more than Kennedy would have had he not been killed. Yet post-1960s America would have been different still after 8 or even 16 years with a Kennedy in the White House (had Bobby Kennedy survived and won the democratic nomination and 1968 election).

Away from the successes and failures of his administration, looking back at Kennedy as an individual as I and many have been doing over recent weeks, the most striking thing is how enigmatic a figure he remains. Many have said that even when he was alive he was something of a mystery (just look how few knew about his astonishing capacity for extra-marital liaison). But even with the benefit of 50 years and hundreds of books, it still doesn’t feel like we’ve discovered the true JFK.

Perhaps it will take another 50 years for us to start to get the full measure of the man, but there’s no question that were Arthur Schlesinger Sr to redo his poll now, JFK would feature prominently. I think he would deserve to do so: his achievements may not have lived up to expectations, but the 20th century would have been poorer and less ambitious without his presidency. But thanks to the actions of an angry young man 50 years ago, where he would place himself in such a poll, we’ll never know.

* Nick Thornsby is a day editor at Lib Dem Voice.