On this date in 1938, Ernest Hemingway returned to Barcelona for the third time during the bloody civil war between Gen. Francisco Franco’s right-wing rebels and Spain’s leftist government. Like most American intellectuals, Hemingway was sympathetic to the loyalists’ side.

The famous American author perceived, correctly, that Franco’s movement was a precursor to fascist movements in Italy and Germany. Several hundred like-minded American communists and fellow travelers from Europe had volunteered to fight Franco’s forces, and most of these volunteers fought in a racially integrated paramilitary unit called the Abraham Lincoln Brigade. Although sympathetic to their cause, Hemingway was not there as a combatant. He went as a war correspondent, albeit one with a point of view.

To be brief, Hemingway considered the Spanish Civil War the first front in a much wider and bloodier war to come, and he believed that if the Western democracies didn’t stop Franco in his tracks, they wouldn’t have much success in stopping Mussolini or Hitler. In the 1980s, these wartime dispatches were discovered in two locations by Hemingway scholar William Braasch Watson, a historian at the Massachusetts Institute of Technology.

“Many sides of Hemingway the newspaperman and writer come through in the dispatches,” Professor Watson said at the time. “Together, they make one thing clear. He was not, as some have asserted, a voyeur, a mere tourist of the Spanish Civil War, but a hard-working, risk-taking correspondent who tried and largely succeeded in becoming the professional reporter and witness that the violence and complexity of the war demanded.”

I’ve written in recent days about the meaning of courage, a trait much in demand as America and the world face a pandemic scourge similar to fascism and communism in one grim regard: It doesn’t differentiate among its victims — almost any adult human being will do. I’ve highlighted presidents and congressional leaders and the medical professionals on the front lines of this war, those who exhibited the trait Hemingway himself defined as the essence of courage: “grace under pressure.”

Those evocative words almost certainly would have been long forgotten by now if John F. Kennedy had not been intrigued by the description, which he used in the opening lines of “Profiles in Courage,” the Pulitzer Prize-winning book he wrote with the help of Ted Sorensen while recovering from back surgery in the mid-1950s.

At the time, Massachusetts’ junior senator was a rising star in Democratic politics. Kennedy was a U.S. Navy war hero in the Pacific, movie-star handsome, and his 1953 marriage to Jacqueline Bouvier was covered as a national news event. But Jack Kennedy was a peripatetic man for whom lying in bed recovering from an operation was not a natural act. Channeling his energies into an account of eight senators who had bucked conventional wisdom and party bosses for the greater good was an appropriate way to use his time productively.

Kennedy’s desire for historical accuracy applied even to his prologue. He’d heard Hemingway’s description of guts, but didn’t know if the famous author had really said it or, if so, whether he’d borrowed it from someone else. So he wrote Hemingway a letter. Where did I find it? In the same place Professor Watson found Ernest Hemingway’s dispatches from Spain’s Civil War — in the John F. Kennedy Presidential Library. How Hemingway’s papers ended up in a presidential library is an interesting tale itself, but one for another morning. What we are interested in today is Sen. Kennedy’s love of a certain phrase and his desire to learn its provenance.

In the days before Google or LexisNexis, it was not easy tracking down quotations. Sometimes politicians would just wing it, as they do today. Kennedy and his speechwriters did this themselves when they got to the White House, attributing pithy quotes willy-nilly to people who never said them. Despite President Kennedy’s assertion, for instance, Edmund Burke did not proclaim that “the only thing necessary for the triumph of evil is for good men to do nothing.” Kennedy also misquoted Soviet Premier Nikita Khrushchev as warning Chinese leaders that in the event of a nuclear war, “the survivors would envy the dead” (it came from a 1960 Herman Kahn book) and twice gave Dante credit for the simplistic notion that “the hottest places in hell” are reserved for those who remain neutral in times of moral crisis.

But in a less hectic environment, while researching his “Profiles in Courage,” Kennedy wanted to make sure of the “grace under pressure” quote. He decided to ask the author himself. Like Hemingway, and many young men sent away to war, the horrors of combat got young Jack Kennedy to thinking about the political failures that led to the killing fields. Kennedy Library archivists have in their possession a four-page draft of an unsent letter that Kennedy addressed to Hemingway musing on the sacrifices young men faced in military service, while making the point that “there is no comparable pressure on the politician to sacrifice all for the public good.”

This missive shows that Jack Kennedy was contemplating the themes of “Profiles in Courage,” soon after he returned from war in the Pacific.

But on July 26, 1955, Kennedy did send Hemingway a letter, care of his publisher. “I am planning to open the book by quoting this definition and stating that the book contains the stories of eight courageous Senators, and the grace with which they endured those pressures,” Kennedy wrote. “Unfortunately, I am unable to find the source of this quotation or verify your authorship of it. I wonder if you recall the phrase and would be kind enough to let me know so I might use it in the manner suggested.”

As Kennedy Library reference archivist Stacey Chandler discovered, Hemingway’s publishing house, Charles Scribner’s Sons, wasn’t much help. No one there could verify the quote, which would be an anticlimactic ending to this story except for two fascinating footnotes. First, Kennedy’s own editor, Evan Thomas of Harper’s, found the source of the quote on his own, and it was indeed Hemingway’s. Thomas found it buried in a 1929 New Yorker article by Dorothy Parker, which is its own little historical gold nugget.

In addition, it seems that Ernest Hemingway was as charmed in 1961 by America’s dashing young president as the rest of us. Asked by the Kennedy inaugural committee to provide his reaction to the inauguration, Hemingway wrote the following:

Watching the inauguration from Rochester there was the happiness and the hope and the pride and how beautiful we thought Mrs. Kennedy was and then how deeply moving the inaugural address was. Watching on the screen I was sure our President would stand any of the heat to come as he had taken the cold of that day. Each day since I have renewed my faith and tried to understand the practical difficulties of governing he must face as they arrive and admire the true courage he brings to them. It is a good thing to have a brave man as our President in times as tough as these are for our country and the world.

Carl M. Cannon is the Washington bureau chief for RealClearPolitics. Reach him on Twitter @CarlCannon.