“Today the challenge of political courage looms larger than ever before,” Sen. John F. Kennedy wrote in 1956, five years before he became president. These words came from his Pulitzer Prize-winning work, “Profiles in Courage,” a biographical portrait of eight senators who took principled and unpopular stands that put them at odds with their parties and constituents but that they felt were morally necessary for themselves and for the country.

While written more than 60 years ago, Kennedy’s book offers a useful guide for understanding why so few members of the current president’s party seem to be holding him to account. Kennedy observed that the wish to be liked by colleagues, the pressures to act with party loyalty, the impulse to reflect the preferences of the majority of their constituents and the desire to secure reelection combine to make true political courage extremely rare. Taking unpopular stands jeopardizes all of these.

But it was also Kennedy’s belief that there are things more important than reelection and more significant than popularity. At the top of his list stood the preservation of democratic principles and institutions, a willingness to defend them and a readiness to make sacrifices on their behalf.

In some ways, Kennedy was sympathetic to politicians struggling to reconcile their personal conscience with their political agendas and the national interest: “If the American people more fully comprehended the terrible pressures which discourage acts of political courage, which drive a Senator to abandon or subdue his conscience, then they might be less critical of those who take the easier road — and more appreciative of those still able to follow the path of courage.” But because it was so rare, and so vital, it was that much more important to understand.

Central to Kennedy’s analysis was what, exactly, would cause a politician to take a stand on an unpopular course?

Kennedy had been thinking about that question for over a decade. His first book, “Why England Slept,” published in 1940, asked why Britain’s leaders had failed to more vigorously oppose popular resistance to rearming in the mid-1930s. His answer then was that political leadership in a democracy was bound, and constrained, by popular sentiment. This was not a defense, Kennedy claimed, of a British leadership that had left the country poorly prepared for the outbreak of war with Nazi Germany but rather an examination of the general circumstances that had made them less willing, and less able, to defy widespread popular sentiment on behalf of the nation’s long-term interests.

These questions took on a particular urgency against the backdrop of the Cold War and McCarthyism, a time when it was Kennedy himself who lacked courage. As fear of widespread communist influence gripped the nation, Sen. Joseph McCarthy (R-Wis.) turned legitimate concerns about Soviet infiltration of the American and British governments into national hysteria. Accusing hundreds of American officials of treason with little regard to evidence, McCarthy led an anti-communist witch hunt that resulted in one of the largest political repressions in the history of the United States.

For years, political leaders of both parties were largely cowed by McCarthy and refused to challenge him, even as his attacks on American political norms and the integrity of its institutions grew increasingly reckless. Finally, in 1954 a backlash against McCarthy led to his censure by the Senate, fueled, as one of his leading Republican critics put it, by “his threat to the very traditions and foundations of our orderly democratic procedures.”

Kennedy was the only Democrat to abstain from censuring McCarthy. Though recovering from back surgery, he did have the ability to vote. Yet he chose not to, deferring to McCarthy’s popularity in Massachusetts. As a result, detractors called “Profiles in Courage” Kennedy’s “act of contrition” for his own lack of courage. (Kennedy would also face controversy over whether he or his aide Ted Sorensen had actually written the book, although most researchers have concluded that Kennedy wrote the first and last chapters — the thematic statements on political courage — on his own.)

Thinking about his conspicuously non-courageous stance on McCarthy and eyeing a presidential run in the near future, Kennedy returned to the issues he had first raised in 1940. Over what issues, and under what circumstances, would a politician defy his party, anger his constituents and risk political oblivion? Where was the line, and what was the balance, between satisfying local concerns and defying them on behalf of larger national obligations?

To answer those questions, he turned to the historical record, profiling eight senators who had been thrust — some eagerly, others unwillingly — into just such a role. Ranging from John Quincy Adams to Sam Houston to Robert Taft, the work was bipartisan, featuring Democrats and Republicans (and Federalists and Whigs, for that matter). In each case, Kennedy examined the pressures that inhibited politicians from acting with courage.

The senators profiled were as different as the diversity of causes they championed. “Some showed courage throughout the whole of their political lives,” Kennedy wrote; “others sailed with the wind until the decisive moment when their conscience, and event, propelled them in the center of the storm.” But for each it was the dictates of both moral conscious and national unity that persuaded him to “to push [his] skiff from the shore alone” into a hostile and turbulent sea.

In Kennedy’s telling, extraordinary circumstances prompted acts of political courage. In the wake of British attacks on American shipping, John Quincy Adams sided with the Jefferson administration, which was unwilling to appease the hostile acts of a foreign adversary even if it resulted in economic harm. In so doing he defied the will of both his Federalist Party and his home state of Massachusetts, which had close economic ties to Britain. When a storm of political protest ensured — which included the censure of his own mother — he resigned his seat.

Kennedy also profiled the actions of Daniel Webster, another Massachusetts senator who defied his party and his constituents. Webster helped broker the Compromise of 1850, which defused the immediate political crisis between the free and slave states, but earned him broad condemnation in the northern press and made him unelectable in Massachusetts. While Kennedy praised politicians who had remained steadfast to principle, he also emphasized that in the American political system compromise often required courage, and indeed was necessary to the functioning of a democratic nation.

Those stories, like the others in the book, allowed Kennedy to make several broader points about national politics. First, courage required more than words, it required action. And it required taking action with the full knowledge that there would probably be consequences, both personal and national. True courage, according to Kennedy, meant a willingness to live with those consequences — even if they meant electoral defeat.

Though “Profiles in Courage” was largely concerned with matters of domestic politics, what emerges from Kennedy’s book is a defense of democracy against its authoritarian rivals. Authoritarian governments impose their vision on society. In democracies, it is up to the people, and, according to Kennedy, “we will get the kind of political leadership, be it good or bad, that we demand and deserve.” But Kennedy emphasized democracy requires more than “popular government and majority rule.” To remain free and open, democratic societies demand leaders willing to “exercise their conscientious judgment,” when faced with the “choice of courage or compliance.”

In “Profiles in Courage,” Kennedy was grappling with the most admirable, perhaps even the most essential, political virtue in a representative democracy, knowing that he had not yet displayed it himself. He was doing so in the midst of sharp partisan division at home and heightened threat from aggressive authoritarian states abroad. Attempting to understand what circumstances made political courage possible, Kennedy hoped to inspire similar actions.

In the opening sentence of the book, Kennedy cited Ernest Hemingway’s description of courage as “grace under pressure.” Kennedy wasn’t the only one inspired by these words. John McCain, for one, has written that Hemingway’s characters “showed me how and why to be brave, how a real hero lives and dies.”  It’s probably too much to hope that the simple act of reading a book would inspire similar acts. Kennedy recognized as much, concluding with the observation that “the stories of past courage can define that ingredient — they can teach, they can offer hope, they can provide inspiration. But they cannot supply courage itself. For this each man must look into his own soul.”

Kennedy’s work provides a useful reminder that fear of censure is a powerful motivator that more often than not discourages acts of political courage. But it also stands as a statement that such acts are essential to the unity, safety and survival of democracy.