Donald Trump isn't a big policy guy. Or a big respect guy.

This anecdote, from a book set for release next week by former Trump White House aide Cliff Sims and first reported in The Washington Post, is illustrative of both of those facts:

"Sims recounts one time when (Paul) Ryan was in the Oval Office explaining the ins and outs of the Republican health-care bill to the president. As Ryan droned on for 15 minutes, Trump sipped on a glass of Diet Coke, peered out at the Rose Garden, stared aimlessly at the walls and, finally, walked out.

"Ryan kept talking as the president wandered down the hall to his private dining room, where he flicked on his giant flat-screen TV. Apparently, he had had enough of Ryan's talk. It fell to Vice President Pence to retrieve Trump and convince him to return to the Oval Office so they could continue their strategy session."

WHAAAAAAAT?

Just to provide some context here: The Republican speaker of the House is talking to the Republican President of the United States about a Republican effort to repeal and replace the Affordable Care Act, a law that Trump had railed against for the better part of two years on the campaign trail. This is not a small deal. Nor is Ryan a person who has no power over Trump's agenda.

And yet, Trump treated Ryan, according to Sims' book, like a sub-human. Can you imagine someone -- in a meeting -- simply wandering off to watch TV in another room while you were talking? No, right? And, if they did, you would think a) is something wrong with them or b) that dude is the rudest person I have ever met.

Except that in this instance the "dude" in question is the President of the United States -- which is all the more revealing, and concerning.

Revealing in that it's clear from the episode that Trump had zero interest in the details of a policy on which, theoretically, much of his political fate rested. Trump decried Obamacare as the worst law ever and insisted that if he got into the White House, he would personally ensure its removal and replacement. And yet, once in office, Trump apparently couldn't be bothered to, you know, pay attention to Ryan for 15(!) minutes. Because policy details carry no interest for him.

This is nothing new, of course. As a candidate, Trump wasn't even willing to fake interest in policy specifics. This, from a July 2016 Politico piece, is indicative of his broader approach:

"The Trump campaign is untraditional in almost every way, but considering the real possibility of a President Trump, the candidate's flagrant indifference to the details of public policy is particularly remarkable. He has said he forms his views through instinct and intuition rather than 'deep analysis.' He has boasted that his main policy adviser is himself and the advisers he does have say he doesn't read briefing papers. He has mocked Hillary Clinton for surrounding herself with 'eggheads' and churning out reams of wonky government reform proposals. Senate Majority Leader Mitch McConnell, who will be speaking on Trump's behalf at this week's Republican convention in Cleveland, recently said 'it's pretty obvious he doesn't know a lot about the issues.'"

Trump doesn't believe details really matter. What matters is winning -- or at least the ability to declare yourself the winner. The policy points are something, in his mind, for the nerds to work out.

He's a closer. And closers don't worry too much about every niggling little detail.

What's concerning in all of this is how Trump treated another prominent leader within his own party. The utter disrespect of simply walking away when someone is talking -- and turning on a TV in another room -- is colossal. That the vice president of the United States had to be called on to convince Trump to come back into the room and talk to Ryan is startling stuff. (Nota bene: Yes, Ryan had been very wary of Trump as a candidate and had distanced himself from Trump in the wake of the release of the "Access Hollywood" tape. But still...)

And for me, it raises this question: If Trump treats his supposed political friends this way behind closed doors, how must he talk about -- and treat -- his political rivals? And what does allowing -- and enabling -- behavior like that from the President of the United States mean about the temperament and mindset of the most powerful man in the country?

The answer is: Nothing good.