The passage, from a book read three decades back, came to mind not long ago. A tweet-driven tumult was, as usual, roiling Washington. Surly and defiant, President Trump was ensconced in the White House, lashing out like King Lear with a cellphone. The issue of the hour was our policy toward a defiant North Korea, and the president had chosen that moment to boast that his nuclear button was bigger than Kim Jong-un’s — hardly an Achesonian diplomatic strategy.

Which doubtless would have pleased, rather than troubled, Trump, who, like Miranda in “The Tempest,” looks upon each day as a “brave new world” that offers him fresh opportunities to star in a global drama of his own direction. Shifting between cable news and my own Twitter feed, I recalled the historian Barbara W. Tuchman’s observation in her 1984 book “The March of Folly: From Troy to Vietnam.” “Wooden-headedness” in statecraft, which she defined as “assessing a situation in terms of preconceived fixed notions while ignoring or rejecting any contrary signs,” has clearly become a prevailing factor in our politics. As Tuchman wrote, wooden-headedness was best captured in a remark about Philip II of Spain: “No experience of the failure of his policy could shake his belief in its essential excellence.”

Why did the Trojans allow the Greek horse within the gates? How did the Renaissance papacy so badly misjudge the moment, accelerating the Protestant Reformation? What could the British ruling class have done differently to keep the American colonies within London’s reach? Who, if anyone, could have prevented Washington’s tragic misadventure in Vietnam? These were Tuchman’s topics, and now, in our own time, we are forced to ponder the why, the how, the what and the who about America in the Age of Trump. “A prince, says Machiavelli,” Tuchman wrote, “ought always to be a great asker and a patient hearer of truth about those things of which he has inquired, and he should be angry if he finds that anyone has scruples about telling him the truth. What government needs is great askers.” To put it mildly, though, the Trump White House seems more “Shark Tank” than Brain Trust.

Tuchman’s literary legacy is various and important. She wrote well about many things, including the coming of World War I (“The Guns of August,” a favorite of John F. Kennedy’s, won the Pulitzer Prize in 1963), the Black Plague (“A Distant Mirror”), the Far East (“Stilwell and the American Experience in China”) and the American Revolution (“The First Salute”). There is something notable, though, about “The March of Folly,” a collection of sketches about mature countries getting things woefully wrong. ...