Nancy Pelosi and Chuck Schumer, who were given time immediately following Trump to present a rebuttal, clearly expected and were ready for that. In ticking off reasons that an expensive and expansive border wall wasn’t needed, Pelosi kept saying, “the fact is,” “the fact is.” It was a mantra meant to humiliate Trump, which is a sport that she is developing an ever greater taste for.

When it comes to the border and the wall, Trump’s willful estrangement from reality is so profound that network executives and newspaper editors spent part of Tuesday in strategy sessions about how to respond to his inevitable barrage of falsehoods. Should there be a crawl of words on the bottom of the television screen to correct him in real time? Could fact checkers work speedily enough to post rebuttals online within minutes of his misrepresentations, before they took root? This is where we find ourselves. Other presidents have been untrustworthy, and others have had to be called out on it. But not like this. This is surreal.

It’s a function of, more than anything, his ego, his vanity, to which the television networks, furloughed federal workers — all Americans — are hostage. He’s not remarkable among presidents in having a high opinion of himself and in desperately wanting others to share it. A robust measure of arrogance and some degree of neediness are what make the grind of the campaign trail and the glare of the media bearable. And all presidents want to rack up triumphs that make them look and feel large. But none in my lifetime has spun so many falsehoods in the service of that. None has been so naked in his hunger for that heft.

To live with his resounding defeat by that “nasty woman” in the popular vote, Trump had to invent the specter of millions of illegally cast ballots. He never did produce any evidence of that. To not feel eclipsed by President Barack Obama, he claimed there was a media conspiracy to undercount his inauguration crowd. But photographs don’t lie. Not the way a president does.

The day after his inauguration, in a visit to the C.I.A. headquarters, against a backdrop of stars that symbolized men and women who had been killed on the job for America, he used his remarks to tally his appearances on the cover of Time magazine. “I think we have the all-time record,” he said, but “we” as usual meant “I.”

There’s no occasion unsuitable for bragging, no mission more vital than the exaltation of Trump. When, over the recent Christmas holiday, he at last paid a visit to a combat zone and spoke to American troops in Iraq, he seemed less intent on thanking them for their service than in having them thank him. He dwelled on a pay increase that they had received and claimed — erroneously — that they had gone without one for 10 years, until he came along.

“We got you a big one,” he said. “I got you a big one. I got you a big one.” I. Big. That’s the Trump credo in two words.