“I want to speak to you tonight about the need for us to lower the temperature in our politics,” Mr. Biden began. He asked Americans to remember that “while we may disagree, we are not enemies. We’re neighbors. We’re friends, coworkers, citizens, and most importantly, we’re fellow Americans.”

President Reagan, after recovering from being shot in 1981, spoke to a priest about his new outlook on life. “Whatever time I’ve got left now,” he said, “belongs to the Big Fella upstairs.” While no good can come from an assassination attempt, a bad reaction to one can make things worse. Reagan chose to see it as a positive.

Mr. Biden was also inspired to hit uplifting notes. “Everyone must be treated with dignity and respect,” he said, “and hate must have no safe harbor. … We must get out of our silos where we only listen to those with whom we agree.”

It was as if he had never cast “MAGA Republicans” as “un-American,” and, along with supporters, hadn’t spent years calling Trump a “threat to democracy,” likened him to Adolf Hitler, and warned that his election would result in a dictatorship.

If this signaled Mr. Biden relaunching his campaign, the nation will be far better for it. “We do not know the motive of the shooter yet,” Mr. Biden said of the gunman, Thomas Crooks. He then condemned “political rhetoric in this country” that “has gotten very heated.” He told the nation, “It’s time to cool it down.”

Mr. Biden went on to list instances of political violence against “members of Congress in both parties,” “a violent mob attacking the Capitol on January 6th,” the assault on Speaker Pelosi’s husband — which had no political motive — and the plot to kidnap Governor Whitmer of Michigan, involving FBI informants.

Only after these cherry-picked examples did Mr. Biden mention the “attempted assassination.” He condemned “violence in the streets,” but omitted Black Lives Matter and Antifa, assaults on members of the Trump administration at restaurants, and the potential assassin captured outside Justice Kavanaugh’s home.

The most positive part of the speech was Mr. Biden’s recasting the election not as “democracy on the ballot,” as he has often said, but as just another choice for president. “The stakes in this election are enormously high,” he said, followed by another reimagining of the past.