There are an infinite number of questions to ask of history. For instance, is Frederick Douglass being recognized more and more? (Yes, partly because he's doing an amazing job but mostly because he's dating Taylor Swift.) Or here's a basic question we as a species should pose to the 20th century every Aug. 6 (the anniversary of Hiroshima) through 9 (Nagasaki): What if fewer children were killed?

On Aug. 10, 1945, that query was on President Harry Truman's mind. According to a cabinet secretary's diary, the day after the five-ton nuclear weapon nicknamed Fat Man obliterated Nagasaki, Truman "didn't like the idea of killing, as he said, 'all those kids.' "

Lately, President Truman has been in my thoughts. Not because Franklin Roosevelt's death drop-kicked him into the Oval Office unprepared, though that does resonate, but because of his secretary of war, Henry L. Stimson. He had visited Kyoto in the 1920s and persuaded the president to take the city off the list of potential targets for atomic bombs. As Stimson recalled in Harper's in 1947: "Although it was a target of considerable military importance, it had been the ancient capital of Japan and was a shrine of Japanese art and culture. We determined that it should be spared."

Kyoto happens to be my favorite foreign city. I don't know how other Americans are coping with watching our government disintegrate in real time, but one way I lower my blood pressure after reading the news is to get out one of my books on the gardens of Kyoto and scrutinize photos of artfully arranged clumps of rocks and moss. Especially the dry gardens designed by Mirei Shigemori, who is, to me, the Rolling Stones of stationary stones. But for me to indulge in this harmless hobby of studying Buddhist landscape architecture, about a quarter of a million mostly civilian inhabitants of Hiroshima and Nagasaki had to die.

On his Restricted Data blog, about nuclear issues, the historian Alex Wellerstein suggests that when Stimson urged Truman to remove Kyoto from the list of target cities because of its cultural and therefore civilian heritage, the president may have gotten the impression that Hiroshima and Nagasaki were more appropriate industrial and military targets.In his diary on July 25, Truman, either too preoccupied or too oblivious to consider that even industrial cities are packed with noncombatants, records that he instructed Stimson to proceed "so that military objectives and soldiers and sailors are the target and not women and children." Anyone who has ever visited the Peace Memorial Museum in Hiroshima and lingered over the frayed shoe of slaughtered 12-year-old Kazuhiko Sasaki knows how that turned out.

"I don't think Stimson attempted to purposely mislead Truman, though," Mr. Wellerstein added. "Rather, I think the root of Truman's misunderstanding was that he was a very incurious man when it came to nuclear matters." He continued, "He rarely questioned his advisers, rarely analyzed the issues with independent judgment, and he never grappled with the big ideas."

But when he saw the devastation the bomb wreaked, Truman became a sober steward of these destroyers of worlds. He insisted on keeping the decision to use nuclear arms in the hands of the president — seemed like a good idea at the time — and proclaimed in his farewell address, "Starting an atomic war is totally unthinkable for rational men." In a paper Mr. Wellerstein delivered last week at a conference in Hiroshima, he said that after 1945, the president became "dedicated to the idea of a level of control that he had not exhibited during the war — a Truman, perhaps, who saw that lack of control, and lack of understanding, as a fundamental turning point in his life."

After 1945, every subsequent president knew what nuclear holocaust looked like and thus to avoid it. How they did so can be instructive. For example: President John F. Kennedy's thoughtful if lucky handling of the Cuban missile crisis, warding off nuclear war by ignoring his more trigger-happy military advisers. Having just read Barbara Tuchman's book "The Guns of August," about the madcap rush into World War I, Kennedy said, "I am not going to follow a course which will allow anyone to write a comparable book about this time, 'The Missiles of October.' "

Would a more curious mind like Kennedy have made different decisions from Truman in 1945? Probably not — once "the Gadget" worked, it was going to be used. But he might have asked more questions beforehand. What we do know is that in 1962, nuclear holocaust was averted in part because a president read a book and learned from it.

We know that our current president reads neither books nor the Australian prime minister's mood. And thanks to a leaked talk to congressional interns last week, we know that his son-in-law and adviser, Jared Kushner, the administration's supposed voice of reason who is charged with ending the opioid epidemic, brokering peace between Israelis and Palestinians, and presumably proving the existence of God, actually said these words, out loud, to people with ears: "We've read enough books."

On Sunday, the 72nd anniversary of the bombing of Hiroshima, the CNN news scrawl blared, in customary if alarming all caps, a statement from the North Korean state-run newspaper that the United States "will sink into an unimaginable sea of fire on the day when it dares to touch our country by stupidly causing mischief and brandishing its nuclear and sanctions clubs."

On Tuesday, President Trump told reporters that North Korean threats would be "met with fire and fury like the world has never seen."

Oh, dear. Better drag out the Japanese garden books. As with literally every other kind of book, I will never, ever read enough of those.

This appeared in The New York Times Opinion section on August 9, 2017.

Sarah Vowell is the author, most recently, of "Lafayette in the Somewhat United States."

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August 9, 2017

Addendum. Just a reminder. Trump must be removed from office to save he world! Now. This is number 4 of my New York Times marathon posts today.