On his desk in the Hoover Building, the head of the FBI keeps a wiretap order from the 1960s, signed by Attorney General Robert F. Kennedy.

It authorized the Hoover FBI to tap the conversations of the Rev. Dr. Martin Luther King Jr. “It is a single page,” current Director James B. Comey said in a recent speech. “The entire application is five sentences long; it is without fact or substance and is predicated on the naked assertion that there is ‘communist influence in the racial situation.’ ”

That document is, for Comey, a moral lesson about the burden of responsibility that a director of the FBI always must keep in the front of his mind.

That beacon is needed more than ever in the anguished debate in many parts of the country over law enforcement and racial divisions in American society.

After controversies in Ferguson, Missouri, and New York City, Comey’s speech at Georgetown University in Washington was a frank call for openness and dialogue at all levels of law enforcement, including discussions of the latent racial biases that few of us are comfortable talking about.

He spoke frankly of the underlying tensions in poor neighborhoods that frustrate the community and police alike but also the “mental shortcut” that police and others are prey to: “The two young black men on one side of the street look like so many others the officer has locked up. Two white men on the other side of the street — even in the same clothes — do not. The officer does not make the same association about the two white guys, whether that officer is white or black. And that drives different behavior.”

Comey noted that the underlying issues of poverty and family breakdown in neighborhoods are tough but that “this (police) behavior complicates the relationship between police and the communities they serve.”

The Georgetown speech also underlined the reality that Americans ought to appreciate those who put on a badge for the good of society. They are heroes who come in response to a call, whatever the neighborhood, whether the caller is black or white; two New York City officers were cruelly assassinated recently. Comey’s grandfather was a 40-year cop and police chief, and much of the director’s own career was in law enforcement.

All that said, though, he called for mental toughness among officers. “We must better understand the people we serve and protect — by trying to know, deep in our gut, what it feels like to be a law-abiding young black man walking on the street and encountering law enforcement. We must understand how that young man may see us,” Comey said. “We must resist the lazy shortcuts of cynicism and approach him with respect and decency.”

Sometimes a tall order, but the director’s words are wise and reflect the long view that American society’s goal is order and law — that the two are inseparable. A deeper understanding of the community is fundamental to the effectiveness of police at every level.