"You will be our president when you read this note," George Herbert Walker Bush wrote to Bill Clinton, the man who defeated him in the 1992 campaign, denying Mr. Bush the provisional vindication that reelection provides until history has its chance to judge from a distance. Nonetheless, in Oval Office tradition, Mr. Bush left a note for Mr. Clinton to read on taking office, and it echoed the message of transitions past, even between bitter political rivals: "I am rooting hard for you."
Note the pronoun: You will be our president. My president. In our interviews and research into the private relations among these most public men, the pronouns matter. At a time when Democrats and Republicans in Congress talk past each other and their supporters view collaboration as corrupt, presidents talk to, and about, one another in very particular ways.
"President Obama and I didn't talk much about politics when we played golf the other day," Mr. Clinton told us, as we discussed the distinctive code of the "Presidents Club." Mr. Clinton was exhausted that day, he recalled, but "when my president summons me, then I come and I would play golf in a driving snowstorm." Which suggests how far the two men had come since their proxy war in 2008.
The offers of help come, often across party lines, because former presidents know what incoming presidents only learn over time.
On the day Franklin Roosevelt died and Harry Truman found himself suddenly responsible for saving the free world, Herbert Hoover sent a cable. "You have the right to call for any service in aid of the country," Hoover wrote, and to the horror of the Roosevelt loyalists in the White House, Truman took him up on the offer. He invited Hoover to the White House to ask his expert advice about preventing a humanitarian catastrophe across Europe. Once they got past their mutual suspicions, the two presidents formed an extraordinary alliance to move food from the countries that had it to the ones that needed it.
That was only the first of their joint missions. It didn't matter that Truman thought Hoover was "to the right of Louis XIV," he said. They never talked about politics anyway because they had something more important in common. "We talked," Truman said, "about what it was like being president."
So did Dwight Eisenhower and John Kennedy — when they finally got around to talking at all. Here again were two men with little use for each other, after a campaign in which Kennedy portrayed Eisenhower as too staid, even too soft, allowing a supposed "missile gap" with the Soviet Union.
By October 1960, Ike told one Oval Office visitor, "Listen, dammit, I'm going to do everything possible to keep that Jack Kennedy from sitting in this chair."
But upon Kennedy's election, the stakes would change, and so did the conversation. When they met at the White House in December 1960, Eisenhower tried to alert Kennedy to what was coming. "No easy matters will ever come to you as president," Eisenhower warned him. "If they are easy, they will be settled at a lower level." So how you organize your staff matters, he explained, and he wrote that night in his diary that "I pray that he understands it."
Only a few months later, the two men picked up their conversation — following the disastrous Bay of Pigs invasion. The language of presidential transition is formal, instructive, supportive; now that they were both presidents, it was raw.
"No one knows how tough this job is until he has been in it a few months," Kennedy admitted.
"Mr. President," Eisenhower replied, "if you will forgive me, I think I mentioned that to you three months ago."
"I certainly have learned a lot since," replied Kennedy.
And they talked about how the whole thing had gone wrong. But when they talked to reporters afterward, Eisenhower pledged his support; he ordered his fellow Republicans to resist "witch-hunting." The New York Times headline read "Eisenhower Urges Nation to Back Kennedy on Cuba," with a photo of the two men walking together at Camp David. That was a photo Kennedy very much needed.
If ever a president needed the solace of this tight fraternity, it was Lyndon Johnson. Barely an hour after Kennedy died, he walked into the cabin of Air Force One to be sworn in as president, and aides who were like family suddenly jumped to their feet. "It was at that moment I realized nothing would be the same again," Johnson recalled. "A wall — high, forbidding, historic — separated us now."
That night Johnson called both Truman and Eisenhower. "I have needed you for a long time," Johnson told Ike, "but I need you more than ever now."
"Any time you need me, Mr. President," Ike said, "I'll be there."
And indeed he drove to Washington the next day, to view Kennedy's casket lying in state and then sit with Johnson and offer his help. Johnson wanted to know what specifically he should do. So Eisenhower got a legal pad and sat in Johnson's outer office, writing out in longhand what Johnson should say to an emergency joint session of Congress.
He asked the secretary who typed his notes to burn them after and make only two copies, one for Johnson and one for himself.
And what was that advice, from a revered, retired Republican president to a suddenly elevated Democratic one? That Johnson would carry out "the noble objectives so often and so eloquently stated by your great predecessor." Eisenhower knew what the country needed at that moment; it was not a time for partisan positioning.
And so it has been. Though heartsick over his loss in 1976, Jerry Ford helped Jimmy Carter get started on a handful of projects even before Mr. Carter was sworn in. Mr. Clinton called Richard Nixon late at night to talk about Russia and to learn how to organize his day — a mystery that Nixon recalled having as well. Late in his second term, George W. Bush often called Mr. Clinton on Sundays, and the two men talked, mostly about politics, in a coded, sentence-finishing vernacular that a top Bush aide described as nearly unintelligible even to him.
It's true that presidents have their feuds, many of them bitter and long-lasting. But by and large the code remains intact. Just recently, Mr. Bush gently took issue with Barack Obama's energy and tax policies, and then he added, "I don't think it's good, frankly, for our country to undermine our president. I don't intend to do so now."
Nancy Gibbs and Michael Duffy are editors at Time magazine and the authors of "The Presidents Club: Inside the World's Most Exclusive Fraternity." This article originally appeared in the Los Angeles Times.