It would be easy to write off a restaurant’s refusal to serve White House press secretary Sara Huckabee Sanders as distasteful, and leave it at that. But what happened Friday at the Red Hen, a tiny 26-seat dining room in Lexington, Va., could be the canary in a coal mine warning America not to let the political divide aggravated by President Trump pull this nation down a hole of animosity unseen since the Vietnam War era.

Red Hen co-owner Stephanie Wilkinson said her restaurant, located in a county that overwhelmingly supported Trump, typically avoids politics. But she felt compelled to abide by the wishes of her staff and ask Sanders to leave, which she politely did. “I explained that the restaurant has certain standards that I feel it has to uphold, such as honesty, and compassion, and cooperation,” said Wilkinson.

Trump used Sanders’ mistreatment as an opportunity to raise sand, calling the Red Hen “filthy” in a tweet. And U.S. Rep. Maxine Waters, D- Calif., followed up by suggesting more people should refuse service to members of the Trump administration.

With a president so focused on keeping this country divided, one can’t help but worry about its future. Given a chance to show he can unite the country behind a common goal — reunification of immigrant children with parents who entered the country illegally — Trump has failed miserably.

Trump doesn’t seem too bothered by his failure. The 72-year-old has made his political career on calling for protesters to be “roughed up,” mocking a disabled reporter and relishing in name-calling. He knows the political base he wants to keep intact is more inclined to cheer him when he talks about building border walls than protecting immigrant children. It shouldn’t take a national tragedy — or to paraphrase President Reagan, an invasion from outer space — for the president to realize the urgency of building consensus among divergent opinions.

The great American experiment is a daring one that can seem hopelessly ideological at times. The only reason it continues to succeed is that we’ve had leaders who believed it could. We’ve had leaders who remind us, and show us, that people of different races, nations, faiths, ideologies and tongues can come together under a common set of values, such as those enshrined in the U.S. Constitution.

People so different can’t help but fight. What’s different now is that we have a president who gets in the rings and sells tickets. Frustration and outrage among those who oppose Trump’s policy and rhetoric are palpable, and calls for civility often risk condoning his behavior. But this nation can’t rise above Trump’s tactics by stooping to them.

No, civility alone won’t cure what ails America. But the opposite — disregard for mutual respect and decency — is a death knell. Don’t swallow the outrage; channel it. Join protests, block-walk for candidates who share your values, elevate voices of sanity on social media.

Our representatives and senators can also help provide conducive avenues for political action by answering their phones, responding to emails and having open-door meetings with constituents. At a time when too many elected officials refuse to host town halls, sometimes it feels like a restaurant confrontation is the only way to address our nation’s political class face-to-face.

There have been other times when America appeared too divided to ever agree. The 1960s saw antiwar protesters tangle with Love-It-Or-Leave-It gangs and civil rights demonstrators withstand attacks by racists. But presidents whose policies weren’t universally accepted by either group tried to appear willing to hear what each side had to say and be open to compromise to unite the country.

Trump isn’t doing that, and maybe he never will. Maybe he needs more encouragement. Maybe he will listen to people who have been in the same position. Maybe he will listen to the most immediate past holders of the presidency, George W. Bush and Barack Obama, a Republican and a Democrat, who know what it’s like to put aside political calculations for the country’s good.

Neither Bush nor Obama has said much about Trump’s machinations to this point. And Trump has made disparaging remarks about them both. They need to get past that. We look to Obama and Bush to make it clear that Trump is flirting with danger by continuing to pit Americans against Americans. If Trump won’t listen to them, he probably won’t listen to anyone. But for the country’s sake, they need to try.