4. He’s not afraid to rank his own siblings. He wrote that his sister Maryanne, a federal judge, “is really something.” Then he added, “My younger sister, Elizabeth, is kind and bright but less ambitious.”

5. He knows you sometimes have to spend money to make money. As I noted, he justified public spending on a convention center by arguing it would boost the city’s economy and its image. He followed that up with a broader argument about countercyclical spending, whether in the public or private sector:

In the face of a sales drop, most companies cut back on their advertising budgets. But in fact, you need advertising most when people aren’t buying.

6. A Mexican border wall isn’t the first thing he’s boldly proposed that someone else pay for. In 1985, Mr. Trump owned the New Jersey Generals, a franchise in the United States Football League. He signed a prominent quarterback, Doug Flutie, and gave him a salary over $1 million a year, which was very high for the upstart league. After a game when Mr. Flutie gave a “dazzling” performance, Mr. Trump had an idea:

I wrote a letter to Harry Usher, our new commissioner, suggesting that the cost of Flutie’s contract be shared among all USFL owners — on the grounds that Flutie’s promotional value was leaguewide. I knew it was highly unlikely that the other owners would go along — and they didn’t — but my attitude is that you can’t get hurt asking.

7. When he owned a football franchise, he told the coach what plays to run. The Generals had an excellent running back, Herschel Walker, but Mr. Trump felt they weren’t running the ball enough. “I ranted and raved to our coach, Walt Michaels, but it wasn’t until I literally threatened to fire him that he got the point,” he wrote.

His micromanagement of his team’s coach stands somewhat in contrast to his admonition early in the book that “you’re generally better off sticking with what you know.”

8. He hasn’t always hated George Will. In recent years, he’s called the conservative columnist “stupid,” a “political moron,” a “disaster,” “wrong on so many subjects,” and, perhaps most woundingly of all, “boring.” But in 1987, he had nice things to say about Mr. Will, because Mr. Will had written nice things about Mr. Trump’s plan to build a 150-story building on the West Side of Manhattan.

“I’ve always liked Will, because he’s not afraid to challenge fashion,” Mr. Trump wrote. “My only regret was that George Will didn’t have a seat on the City Planning Commission.”

9. He’s known for a long time that generating controversy isn’t always a bad thing. In 1980 he got a lot of bad press (including a negative editorial in this newspaper) for destroying friezes and iron grillwork on the old Bonwit Teller department store building, because preserving them would have delayed demolition that was necessary to make way for Trump Tower. But the criticism had an upside.

The stories that appeared about it invariably started with sentences like “In order to make way for one of the world’s most luxurious buildings...” Even though the publicity was almost entirely negative, there was a great deal of it, and that drew a tremendous amount of attention to Trump Tower... I learned a lot from that experience: good publicity is preferable to bad, but from a bottom-line perspective, bad publicity is sometimes better than no publicity at all. Controversy, in short, sells.

10. He’s also long known that a spectacle can impress people even if there is no substance behind it. In 1982, he wanted Holiday Inn to buy a stake in his casino project in Atlantic City, and he was concerned it would decline because construction wasn’t far enough along. So he told his construction manager to hire a ton of bulldozers and dump trucks to move dirt around the site, so it would look extremely busy when Holiday Inn executives made a site visit. The instructions were simple:

What the bulldozers and dump trucks did wasn’t important, I said, so long as they did a lot of it.

According to Mr. Trump, this display worked: “These distinguished corporate leaders looked on, some of them visibly awed. I’ll never forget one of them turning to me, shaking his head, and saying, ‘You know, it’s great when you’re a private guy, and you can just pull out all the stops.’ ”

Of all the lessons in “The Art of the Deal,” this may be the one most directly informing Mr. Trump’s campaign.