A few days after President John F. Kennedy made a calamitous early misstep—a carelessly planned attempt to invade Cuba and overthrow Fidel Castro, in April, 1961—he invited Dwight D. Eisenhower, his predecessor as President, for lunch. They met at Camp David, in Maryland’s Catoctin Mountains, close to Eisenhower’s Gettysburg farm. Outside the complex’s Aspen Cottage, Kennedy said, “No one knows how tough this job is until after he has been in it for a few months.” Eisenhower replied, “Mr. President, if you will forgive me, I think I mentioned that to you three months ago,” to which Kennedy said, “I certainly have learned a lot since then.”

This purported exchange, repeated in many histories of the time, cannot be found in Ike’s notes on the meeting, but it sounds authentic, given what we know of each man. Kennedy was certainly rattled enough by his early failure to look for advice from the general who’d commanded the Allied Expeditionary Force. Although Kennedy hired a number of smart, if not necessarily wise, advisers, he knew what he didn’t know. He was a serious reader and student of history. Ike and J.F.K. were never particularly friendly, but they both respected the office they’d held, and Eisenhower, a traditional patriot, simply wanted Kennedy to succeed. At Camp David, he offered some enduring Ike-like advice: after urging Kennedy to support, “at least morally and politically,” policies to keep Communist influence out of the Western Hemisphere, he warned, according to his notes, that “the American people would never approve direct military intervention, by their own forces, except under provocations against us so clear and so serious that everybody would understand the need for the move.”

That idea of Presidential understanding and coöperation, and of the high stakes they involve—the unexpressed faith that America’s leaders, past and present, must put the nation’s welfare first—is among the serious casualties of the new Presidency of the former reality-TV star and real-estate brander Donald J. Trump. His burst of tweets on March 4th about his predecessor, Barack Obama—sent between 6:35 and 7:02 A.M. E.S.T., and arriving like an early-morning gust of foul wind—is unforgettable for the glimpse it gave of the disturbances within Trump’s mind. One said, “How low has President Obama gone to tapp [sic] my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!” To that, there’s not much to add beyond what the F.B.I. director James Comey is thought to believe: that this is malevolent nonsense. Above all, the episode bespoke what may be Trump’s most alarming accomplishment: the ongoing desecration of the Presidency.

The idea that Trump, like Kennedy, might in good faith seek the advice of a predecessor seems impossible to imagine; there does not appear to have been any serious consultation regarding the troubled raid in Yemen, on January 29th, which left one American SEAL and some number of Yemeni civilians dead, after which Trump said that the buck did not stop here, with the President, but over there, with the generals. Such a meeting certainly would not happen at Camp David, given Trump’s comments on the retreat: “Camp David is very rustic, it’s nice, you’d like it,” he said. “You know how long you’d like it? For about 30 minutes.” That comment, in the scheme of things, seems at first like no big deal—just another sneering observation on the scale of his sneering observations about the decline of “Celebrity Apprentice,” his former TV show.

But the remark said a lot about someone who seems to have no sense of the history and traditions of an office that, for all the trouble its occupants have caused—including the lies of Lyndon B. Johnson and the criminal behavior countenanced by Richard Nixon—Americans still esteem.

The encampment where J.F.K. and Eisenhower had lunch has, for seventy-five years, offered Presidents solitude, security, and a simulacrum of the American wilderness—a setting ideal for contemplation, or for diplomacy. It’s where Franklin D. Roosevelt, who named it Shangri-La (after the hidden valley in James Hilton’s “Lost Horizons”) met with Winston Churchill, and where Eisenhower, who renamed it after his grandson David, saw the Russian Premier Nikita Khrushchev. It’s where Jimmy Carter spent nearly two weeks, in the late summer of 1978, prodding the Israeli Prime Minister Menachem Begin and the Egyptian President Anwar Sadat to agree on what became the Camp David Accords. Imagine, if possible, how that might have gone if Carter had put Begin and Sadat on display for the golfers and gawkers of a Florida country club, which is where Trump dined with Shinzo Abe, the Japanese Prime Minister, and met with advisers to discuss responses to a provocative missile test by North Korea. (“Wow…the center of the action!!!” one club member wrote on his Facebook page.) Seen in that light, Trump’s contemptuous remark about Camp David became another early warning that, even after taking the oath of office, there would be no end to his vulgarity and mendacity.

He can’t stop himself. Around the time of reports that the Attorney General, Jeff Sessions, had met at least twice with the Russian Ambassador during the Presidential campaign, and then let it slip his mind during his confirmation hearings, Trump was enjoying the company of Harvey Levin, the host and creator of the guerrilla gossip program “TMZ.” The site that first reported this visit, entitymag.com, said that their meeting, in the Oval Office, included a discussion of Levin’s new reality show “OBJECTified,” which featured Trump in its début, in November, who returned the favor with a tweet that he sent a month after he was elected as the nation’s forty-fifth President: “@FoxNews will be re-running ‘Objectified: Donald Trump,’ the ratings hit produced by the great Harvey Levin of TMZ, at 8:00 P.M. Enjoy!”

Hard to enjoy, though; hard to believe, too; and, above all, hard to watch what’s happening to the office and the mission of the Presidency, aided and abetted by men and women who will not be forgiven in the history books that Trump will never read.