WASHINGTON — The five days in 2008 between the Iowa caucuses and the New Hampshire primary were Hillary Clinton’s crucible. They showed what she’s made of and that she should never be underestimated.

After Barack Obama’s overwhelming victory in Iowa, the polls all suggested he was about to deliver the second shot of a one-two punch that would have crippled Clinton’s campaign.

If he had, the once-inevitable front-runner would have lost her chance to fight Obama to a virtual draw in the Democratic contests over the next five months. In turn, Obama might never have seen her as a natural and unifying pick for secretary of state.

Clinton’s comeback was powered by characteristic moves, and then a big surprise.

Reflecting what some praise as her persistence and others see less charitably as doggedness, she loaded her schedule with town halls that wouldn’t end until she had answered every voter’s question.

At a high school in Penacook, a colleague turned to me to dismiss her offerings as “a laundry list of wonkery”— fair enough if the standard of comparison was Obama’s prophetic rhetoric. A CNN account poked fun at her for spending her day “talking … and talking … and talking.” But voters are not journalists: They appreciated her efforts.

That night, Obama made a mistake when an interviewer asked Clinton about her likability problem. (It’s amazing how media stereotypes have a longer half-life than nuclear waste.) Clinton sounded genuine but also wry when she replied to the questioner: “Well, that hurts my feelings.” And when Obama said, “You’re likable enough, Hillary,” he seemed, unintentionally perhaps, snarky and superior. More votes to Clinton.

And the day before the primary, she choked up when a friendly questioner asked her about the grueling nature of campaigning: “How do you do it?”

Her show of emotion shocked those who thought everything about her was bottled up. It reassured many in New Hampshire who refused to see her as an automaton. She delivered a classic Clinton message in the process: “Some people think elections are a game, lots of who’s up or who’s down. It’s about our country. It’s about our kids’ futures. And it’s really about all of us together.”

She won New Hampshire, and the rest is history — a complicated, often painful history that involved losing to Obama, serving in his Cabinet, facing a surprisingly strong challenge from Bernie Sanders and, finally, securing the Democratic presidential nomination that had eluded her.

On Tuesday, she returned to the message of that vulnerable moment in New Hampshire for the template of her critique of Donald Trump. “Bridges are better than walls,” she said. “We believe that we are stronger together.”

For a quarter-century, Clinton has confronted searing criticism and profound skepticism about her motives and her way of doing things. But if this is all you pay attention to, you cannot explain how she got to that victory party in Brooklyn or why she has received tens of millions of votes over two campaigns.

The Hillary Clinton who prevails and wins loyalists, I’d argue, brings together two aspects of the Methodist tradition in which she was raised and, by extension, two sides of the American character.

She embodies the tensions and, sometimes, contradictions of what the theologian Michael Novak once described as the “communitarian individual.” Her individualistic side sees salvation as depending on determination, grit and a dedication to work, and more work. Her communal side (she wrote a book, after all, called “It Takes a Village”) runs through all her policy proposals, the values she lifts up (“all of us together” in 2008, “stronger together” now) and her attitude toward her friends. Those two instincts keep her going.

None of this explains away Clinton’s flaws or blind spots or the mistakes she has made. We’ll hear plenty about those. But these are her standards, and they are the reason why, beyond his assorted electoral weaknesses, Trump is the opponent she would have prayed to face.

The upright Midwestern Methodist who insists that life is about more than deals, who thrives on meticulous preparation, who is better with individual voters than with big crowds, and who always had to get there the hard way believes it from the bottom of her heart when she says that Trump is “temperamentally unfit to be president.” When she takes him on, there will be no authenticity problem.

She didn’t know it during those five days in New Hampshire, but this is the fight she was preparing herself to wage.

E.J. Dionne Jr. is a columnist for The Washington Post. His email address is: ejdionne@washpost.com. Twitter: @EJDionne.