On Independence Day, we often invoke the military sacrifice that enables our Star-Spangled Banner to freely wave. Maine indeed has born more than its share of battlefield sacrifice and time on watch, over generations. Gratefully, we Americans thus should ask ourselves, what should we do with our independence?

Part of the answer starts with the oath all military members and civilian state and federal officers swear. Americans don’t take an oath to a monarch, imperial dynasty, religious order, political party or leader; rather, we swear an oath to a Constitution. It is a manner of governing, and also a promise to work together.

“We the People of the United States,” the Constitution begins, “in Order to form a more perfect Union …” The Founders declared in the very first sentence that we always can and should strive together to create a better version of ourselves.

Abraham Lincoln echoed that vision decades later, while dedicating the Gettysburg military cemetery. One National Park historian said Gettysburg was a “Maine battlefield more than anything else” because of the blood shed by our state’s sons in the pivotal battle that ended this week, 160 years ago. In his famous address there four months later, President Lincoln challenged the audience and indeed the nation, “It is for us the living … to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced.”

And so here “We the People” are, in our time, with our own challenges and worries, wondering how we might advance other kinds of “unfinished work” to make our nation “more perfect.” In doing so, we often look to history.

In history, there is triumph and glory, but also injustice. Consider the state of Maine’s eugenics-minded obliteration of a mixed-race community on Malaga Island in 1912. Two decades later, while developing their master-race policies and plans, Nazi leaders literally came to the U.S. to learn about events and places like Malaga Island. Another century later, Gov. John Baldacci, Gov. Paul LePage and the Legislature all successively apologized for it and took redemptive steps. In bipartisan fashion, they understood that we have to be honest with ourselves. Doing so enables us to improve, which truly honors those in every generation who bequeathed this great nation to us.

A cautionary tale I often hear invoked in floor debates in the State House is that of Nazi Germany. Everyone seems to know how that grim story ended, but far fewer understand the origins. How could an advanced nation of ostensibly decent people, just like ours, perpetrate such atrocities?

Seeking answers this spring, Maine legislators from both the House and Senate visited the Holocaust and Human Rights Center of Maine. Republican and Democratic leadership and rank-and-file members participated. We heard from Erica Nadelhaft, the center’s education coordinator, in a small, solemn auditorium surrounded by many portraits of Holocaust survivors who later settled in Maine. We were reminded about the gradual dehumanization of people, and how the military, the police and security forces, teachers and many civilian leaders had to take an oath to the führer himself. Then a legislator from rural Maine asked Ms. Nadelhaft what she thought was the difference between “patriotism” and “nationalism.” She paused, then replied that true patriotism acknowledges mistakes in an effort to improve, so that one’s country can be the best it can be.

In the United States, our leaders take an oath to the Constitution; to support and defend our architecture for working together; to promise across time to make a better version of ourselves; to constantly journey toward liberty and justice for all.

Our commitment to that journey is what makes America great.

So on this July Fourth, let us recommit to working together on the unfinished work and vexing problems we face. We can make our state and the nation “more perfect.”