“If you don't mind,” he says, “I'm going to put that in my book.”

An American apotheosis is often built on a humbling downfall, and Jimmy Carter has his, too, of course. He came to the presidency as one of the longest long shots in history: With only 2 percent name recognition when he began his primary run, he eventually won 50.1 percent of the national vote to defeat incumbent Gerald Ford. After four tumultuous years, he found himself as widely disliked as almost any president in history. His 34 percent approval rating upon exit was the same as George W. Bush's, according to Gallup; the only modern presidents more hated were Nixon and Truman.

In Carter's case, despite the triumph of a Middle East peace agreement and the normalization of relations with China, despite his claim of having the second-highest success rate of initiatives passed in Congress (LBJ was the first), he was blamed for crippling stagflation, a fuel crisis that led to epic gas-station lines, and a kind of Black Mirror episode in which a grumpy Iranian imam halfway around the world seemed to hold not just 52 Americans but an entire nation, including its president, hostage. Carter so worried over the hostages in Iran that he proclaimed they were the first thing he thought about in the morning when he woke and the last thing he thought about at night during the 444 days of their captivity. To make matters worse, a failed rescue attempt left eight American servicemen dead in the Iranian desert.2

The Carter presidency (1977 to 1981) is partially remembered—and lampooned—for this very afterimage of ineffectuality, of a leaf man lost in the forest with a command for minute details but whose overweening morality eventually left him without political bite or guile. His religiosity also confused people. As the first president from a southern, evangelical-Christian tradition to talk about being “born again,” he was, according to E. J. Dionne Jr., treated by the press as “some sort of Martian.”3 Surrounded by his “Georgia Mafia,” the group of advisers who'd helped make him governor of that state, Carter rode into Washington on a populist wave, as an outsider—and remained one. He took a dim view of Congress, at one point calling the members “juvenile delinquents.” A claim that came to define Carter's microscopy was that, given all the crises in the world, the president himself controlled the sign-up sheet for the White House tennis court. (Carter eventually had to deny the detail.4)

The toothy smile, the oversharing,5 Billy the beer-swilling brother, and a crazed swamp rabbit that seemed to muster an attack on the president as he fished—they all made for good punch lines. Though the true Carter was much more complicated, a combination, as described by historian Garry Wills, of “ferocious tenderness, the detached intimacy, the cooing which nonetheless suggests a proximity of lions.” His mean streak included an intense dislike for Ted Kennedy, blaming the senator for denying him a comprehensive health-care bill.

In retrospect, there's much about the Carter presidency that was shaped by externalities—in particular the Iranian revolution that was at the root of both the second oil crisis and the hostage-taking in 1979—and yet Carter's response to both, epitomized in his famous “Crisis of Confidence” speech on July 15 of that year, was a withering sort of critique. In that address, he famously condemned our American addiction to stuff, our materialism and consumerism. “Too many of us now tend to worship self-indulgence and consumption,” he told us. He called for car pools, thermostats set lower, and obeyance of the speed limit not just as acts of common sense but of patriotism. To watch that speech now is to witness a very unusual sort of political mixing of morality, religion, and country frugality. (It seems telling that people misremember the speech as having been delivered in a cardigan sweater, rather than the suit and tie Carter wore.) Afterward, the White House switchboard lit up, allegedly with callers applauding the president. And yet judging by the reaction to that speech over time—including the election of Ronald Reagan—apparently what we craved was a different kind of bedtime story to solve our problems, not Carter's strict-daddy austerity measures, ones that included solar panels on the White House.

And yet the polls were still even on the Friday before Election Day, 1980; only in the waning moments of the campaign did Reagan's brand provide the more powerful elixir. You can watch the aftermath on YouTube: Carter leaving Washington on Inauguration Day and flying back to Plains with Rosalynn, emerging in cold January rain to huge crowds. Here he is, then: 56 years old, and in the footage he sees his mother, Lillian, to whom he confesses he hasn't slept in two nights, in a flurry of last-minute negotiations to free the hostages. He is home, among his friends and family, and yet there's an air of exhaustion and melancholy. (“Allowing Ronald Reagan to become president,” he said later, “was by far my biggest failure in office.”) Prior to the presidency, he'd owned a prosperous peanut business, but due to mismanagement, he's recently found out he's over $1 million in debt. Not the most auspicious start to a post-presidency.

At the time, America was mostly done with Jimmy Carter. We apparently were unconvinced by his wagging finger, by his stubbornness, by his inability to effectively address the big challenges of the day. Our stature in the world seemed much diminished. He himself talks about his former “arrogance,” that he thought he possessed all the answers somehow. But we kept waiting for Godot to show up—and when he didn't, we turned the page with some disgust. Ronald Reagan brought his California movie-star wattage and conservative duende, and, like that, after a four-year interlude from the Nixonian nadir, the Republican party was seemingly resurrected and would run the table for the next 12 years. Carter's last significant cameo was a visit with the released hostages in Germany at Reagan's behest, one that left him moved and shaken. Then he retreated to write his memoirs from the 5,000 diary pages he'd kept during his White House years, and to pay back his debts.

As summer gave way to fall in Plains, and fall to winter, as winter relented to spring and the plums, figs, and sugarberries came back around, the cars kept pulling into the lot at Maranatha Baptist, greeted by George, who kept one eye on the heavens, looking for the Space Station. Back in February, Rosalynn took ill—“very, very ill” was how Mr. Jimmy had it. It had to do with her “insides,” repercussions from an operation years ago, and required another operation, from which recovery was slow and arduous. Mr. Jimmy was going up to Atlanta twice a week to see her and abide with her and spend the night. Even he seemed a little more wobbly on his feet now, even more elfin with age. Sometimes Miss Jan set up a chair nearby that he never used, or a glass of water. He appeared from the wings at 10 A.M. each Sunday, flashing that disarming smile, and those hooded ice-blue eyes, the full effect of which, when he registers surprise or joy, was startling, almost boyish. He spread the notes he never referred to on the podium, saying, “Good morning, everyone!”

Beaming back at him were Connecticut and Arizona, a family from England, scatterlings from Taiwan, Japan, Scotland, Congo. “Do I have any kinfolk here today?” he asked. A man raised his hand. “You a kin to me? We'll have to fish together.”

Then he was off again, musing about those statues of Confederate war heroes, whether they should be torn down: “When I see a statue of a soldier from the Confederate side, I feel like I might admire it because it might represent my grandparents.” Or sounding a little like Bernie Sanders, repeating beliefs he's held long before we bothered listening to Bernie Sanders. “Today if you can't raise $200 million, you can't be the nominee,” he said, “and it costs $1 billion by the two candidates once they get done running. We've become an oligarchy ruled by wealth rather than a true democracy.”

On a Sunday before Christmas, he claimed he'd just been on his last quail hunt. He was down in Leesburg with friends and noticed, while walking through the woods, that his balance was off. Rather than endanger anyone, he knew his shooting days were over. “I had to give up running when I was 80 years old, so age catches up with everybody,” he said.

When did Jimmy Carter forgive us? The answer to that was simple: The first day Mr. Jimmy, a citizen again, invited us all back to Plains, Georgia, for Sunday school, the day his ex-presidency began in earnest.

In March, he reminded us that he was cancer-free. Maybe he could go on forever.

So much was happening so quickly now: North Korea, Syria, Iran, Russian meddling, trade wars and porn stars, stock-market roller coaster, etc. He'd been in Egypt and met with the grand imam. He'd huddled with a White House official to brief him on the North Korea situation. (“I have a fairly good friend in the White House,” he said, then deadpanned, “Just one. I have to admit, it's not the president.”) He'd recently sent a message to Putin, telling him that with the help of Google they'd constructed a “map of belligerence in Syria.” He wondered if Putin himself would be “interested in having it so he would bomb the right people.” Here we were, then, humans evolved to a high point, an apex, trying to kill each other, both figuratively and literally.

To inoculate myself, I'd tried to boycott the news, but then couldn't. It seemed to boil down to a peculiar choice at this moment, between being apoplectic or apathetic. Was there a medical diagnosis for the national diminishment of hope? And on Sunday, Mr. Jimmy stood up in front of the world as it arrived to Plains—speaking before some sort of unspoken resistance movement—and calmly kept right on teaching his lessons.

On the last Sunday I was in the crowd, Mr. Jimmy was talking about Tolstoy's War and Peace. He was wondering if any of us had read it, and an uncertain hand or two went up. “It's about ordinary people,” Mr. Jimmy said with a flash of excitement. “The message I got from it was that even in Russia, that was controlled by an emperor, it was the common, ordinary people that shaped the outcome of the major historical events. And if that's true in a country that's had an emperor, who was a dictator, it must be true in our country. You see, that's the transition that I want us to make this morning. We, individual citizens [in] a democracy, we are the ones that determine what kind of country we have.”