All this will force even liberals to reappraise the Obama presidency. Lincoln’s political reputation went from being “the original gorilla” (as Edwin Stanton, his future secretary of war, once called him) to being celebrated, in the words of Ulysses Grant, as “incontestably the greatest man I have ever known.” Obama’s political trajectory, and reputation, are headed in the opposite direction: from Candidate Cool to President Callow.

That reappraisal is going to take many forms, not least in the international goodwill Mr. Obama’s presidency was supposed to have brought us. But since the occasion of this column is the Gettysburg sesquicentennial, it’s worth turning to the question of the president’s once-celebrated prose.

Abraham Lincoln spoke greatly because he read wisely and thought deeply. He turned to Shakespeare, he once said, “perhaps as frequently as any unprofessional reader.” “It matters not to me whether Shakespeare be well or ill acted,” he added. “With him the thought suffices.”

Maybe Mr. Obama has similar literary tastes. It doesn’t show. “An economy built to last,” the refrain from his 2012 State of the Union, borrows from an ad slogan once used to sell the Ford Edsel. “Nation-building at home,” another favorite presidential trope, was born in a Tom Friedman column. “We are the ones we have been waiting for” is the title of a volume of essays by Alice Walker. “The audacity of hope” is adapted from a Jeremiah Wright sermon. “Yes We Can!” is the anthem from “Bob the Builder,” a TV cartoon aimed at 3-year-olds.