In the preface to “Profiles in Courage,” published in 1956, John F. Kennedy, then the junior senator from Massachusetts, offers an inventory of the pressures that senators face which “discourage them from acts of political courage.” First, there is the human craving to be liked. Politicians are no different from everyone else, Kennedy writes, in that they “prefer praise to abuse, popularity to contempt.” Lawmakers tend to want to “get along with our fellow legislators, our fellow members of the club, to abide by the clubhouse rules and patterns, not to pursue a unique and independent course which would embarrass or irritate the other members,” he continues.

There is, too, the matter of political survival. This is not an entirely self-centered consideration. After all, senators who are voted out of office will no longer be around to fight for their principles. Losing reëlection does not affect the senator alone but also his or her family and friends and supporters—many of whom sacrificed their time and resources to help the senator get elected to public office. The trappings of the Senate—its prestige, access to power, and other privileges—are difficult to give up as well. “Thus, perhaps without realizing it,” Kennedy writes, “some Senators tend to take the easier, less troublesome path to harmonize or rationalize what at first appears to be a conflict between their conscience—or the result of their deliberations—and the majority opinion of their constituents.”

Finally, Kennedy describes the pressures of the constituents themselves: “the interest groups, the organized letter writers, the economic blocs and even the average voter.” These pressures are myriad, endless, and often conflicting. Even if the numbers of a particular constituency are not large, they can be difficult to ignore. Kennedy characterizes these factors as the “most significant source of pressures which discourage political courage in the conscientious Senator or Congressman.”

Highlights from President Trump’s State of the Union address.

More than six decades later, Kennedy’s accounting of all of the forces that prevent legislators from taking unpopular stands provides some measure of the bravery of the speech that Mitt Romney delivered on the Senate floor on Wednesday. Shortly before all of his Republican colleagues voted to acquit Donald Trump in his Senate impeachment trial, Romney said he believed that the President had committed “high crimes and misdemeanors.” “The President asked a foreign government to investigate his political rival,” Romney said. “The President withheld vital military funds from that government to press it to do so. The President delayed funds for an American ally at war with Russian invaders. The President’s purpose was personal and political. Accordingly, the President is guilty of an appalling abuse of the public trust.” Romney acknowledged in his speech that his vote was a symbolic one. He was also aware, as a frequent critic of the President, that the power of the “organized letter writers” is magnified today, by all of the digital age’s tools, which a populist demagogue President can use to incite his supporters.

“I am aware that there are people in my party and in my state who will strenuously disapprove of my decision, and, in some quarters, I will be vehemently denounced,” Romney said. “I am sure to hear abuse from the President and his supporters. Does anyone seriously believe I would consent to these consequences other than from an inescapable conviction that my oath before God demanded it of me?”

Romney’s career in public service has long been characterized by discordant narratives. He has sought to convey to voters his deep sense of civic duty and his desire to make a contribution to his country, while critics of both parties have held that he is a capricious politician lacking in core convictions. On Wednesday, Romney may have finally resolved that conflict for posterity. “I will tell my children and their children that I did my duty to the best of my ability, believing that my country expected it of me,” he said. “I will only be one name among many, no more or less, to future generations of Americans who look at the record of this trial. They will note merely that I was among the senators who determined that what the President did was wrong, grievously wrong.”