We can look back from this slum of a year by revisiting Barack Obama’s “A Promised Land.” It’s a reminder of a president who could lead the country and write a marvelous book, instead of a departing president who has misled the country and probably never even read a book.

Obama’s newest effort is 700 pages, and for good reason. He was paying attention to detail. He wants us to know how things happened in his White House years, and what it felt like as a man and not just as a politician.

Maybe the most heart-stopping moment – and there are plenty of them – comes at the end of the book, as Obama and some top national security officials watch live pictures of the team closing in for the killing of Osama bin Laden.

“This was the first and only time as president that I’d watch a military operation unfold in real time,” Obama writes, “with ghostly images moving across the screen. We’d been following the action for barely a minute when one of the Black Hawks lurched slightly on descent. … The helicopter had clipped the side of one of the compound’s walls.

“For an instant, I felt an electric kind of fear. A disaster reel played in my head – a chopper crashing, the SEALs scrambling to get out before the machine caught fire, a neighborhood of people emerging from their homes to see what happened as the Pakistani military rushed to the scene.”

You’ll feel like you’re sitting in the room with your heart stopping before the coded message confirms that revenge has finally been taken on the architect of Sept. 11, 2001.

But it’s not just the series of political dramatics that stay with you through this book – it’s the sense of a grownup who’s in charge over eight years, who was paying serious attention to the myriad of issues crossing his desk day and night.

It’s a sharp contrast with this man dragging his knuckles across the floor as voters and a whole legion of judges force him from office. Whatever Donald Trump’s gifts were – and he surely had some, because nearly half the country voted for him – history’s never going to remember him as a man paying attention to details.

The New York Times’ national security correspondent David Sanger recently described Trump as “a president with no experience, more interested in cutting deals than designing a long-term strategy – and an unwillingness to sit for intelligence briefings, much less discussions” of adversaries like Russia and China.

And Trump’s the same guy who’s been publicly indifferent to more than 300,000 COVID-19 deaths, and the crumbling of the U.S. economy, and the millions of Americans desperate to feed their families and hold onto their homes – indifferent, because he’s been so caught up in his seditious effort to overturn the legitimate results of the 2020 presidential electorate.

In “A Promised Land,” does Obama paint himself as a perfect president? Lord, no. He’s quick to second-guess himself, and to admit mistakes of judgment.

But he shares the thinking that went into those mistakes – the sense of history, and of politics, and the Republican opposition that stood in his way just to score momentary points.

His biggest political mistake comes right away. Obama thought he could find common ground with Republican leaders. He thought he could reason with them. He didn’t imagine the brick wall they’d throw up to keep him from any sense of triumph, no matter the good it might bring the country.

The biggest culprit – Senate Majority Leader Mitch McConnell – is still there, of course. But if Democrats somehow pull off a couple of wins in Georgia early next month, it could change the course of history.

“A Promised Land” reminds us, it’s the same McConnell who opened the Obama White House years by declaring his No. 1 goal was keeping Obama from getting re-elected – and never mind what gutter tactics he had to use along the way.

A former Baltimore Sun columnist and WJZ-TV commentator, Michael Olesker is the author of six books. His most recent, “Front Stoops in the Fifties: Baltimore Legends Come of Age,” was reissued in paperback by the Johns Hopkins University Press.