In 1972, no American was more associated with white supremacy and racial segregation than George Wallace, then the governor of Alabama and a candidate for president. But after an assassination attempt that spring left him paralyzed, an unlikely visitor turned up at his hospital bedside.

Shirley Chisholm, the first Black woman elected to Congress, stayed there for about 15 minutes. They prayed together, and he wept. But the governor also seemed concerned that Ms. Chisholm’s supporters would be unhappy she was kind to him. “What are your people going to say?” he asked.

Indeed, Ms. Chisholm would later recall that the hospital visit nearly cost her re-election. But that was beside the point.

“I wouldn’t want this to happen to anybody,” she remembered telling Wallace.

In times of national trauma or crisis, political leaders have tended to make appeals for unity and to a collective sense of values, hoping to bring down the temperature even when some Americans lust for revenge. In the days after the Sept. 11 terrorist attacks, for instance, President George W. Bush vowed to bring the attackers to justice but also visited an Islamic cultural center and declared, “Islam is peace.”

It strains the imagination to picture what the analogue of that declaration or the Wallace-Chisholm moment would be today, as another spasm of political violence this month ripped open old cultural and political divisions. On Sept. 10, the conservative activist Charlie Kirk was assassinated as he spoke on a Utah college campus. A sniper carried out a similar attack two weeks later in Dallas, the authorities said, firing indiscriminately at a U.S. Immigration and Customs Enforcement field office and killing one detainee.