The United States changed fundamentally and permanently between 1865 and 1870. A constitutional renewal now known as the Second Founding, prompted by the bitter and tragic Civil War, saw ratification of three amendments that confirmed the legal equality of all persons born or naturalized as United States citizens.

The Thirteenth Amendment, formally ending slavery, was ratified on December 6, 1865, by all 36 states (the recalcitrant Kentucky, New Jersey, Delaware, and Mississippi had rejected it the first time around). Over the next five years, the states went on to ratify the Fourteenth and Fifteenth amendments, which extended citizenship to former slaves and gave the franchise to them and to all citizens (except women).

Celebrating the Second Founding brings back into public view, and into public discussion, the ways in which slavery and its aftermath have shaped America’s collective identity. After the revolution, a torturous constitutional accommodation was required for the continuation of slavery. Then came the redemptive moment, in the wake of civil war, when the constitutional frame was corrected and a different future for the country became possible—but not without a hard struggle to move from mere legal emancipation to real freedom and equality.

That struggle has lasted 150 years and it isn’t over. It lives on today in the legal debates about what the Constitution and its Second Founding amendments really mean. Those debates take place in courts around the country, including the Supreme Court, and resonate in college and university admissions programs, in places of employment, and in police departments. Beyond these domains, the U.S. is also struggling to understand the meaning of equality in schools, neighborhoods, and people’s daily lives.

But there’s also been progress since the Second Founding. The Nineteenth Amendment extended the right of suffrage to women in 1919. The civil-rights movement of the 1960s led to the important legislative accomplishments of the Voting Rights Act of 1965 and the Civil Rights Acts of 1964 and 1968. In 2008, an African American was elected president of the United States.

Political memory is composed in part of grand public gestures that cause us to fix our collective attention on important events or figures. Many of these gestures—July 4 comes to mind—become so routine that they lose their authentic meaning and the opportunity for genuine public reflection. But not so, or at least not yet, with regard to the Second Founding. There is the chance that its observation will be consequential and that it will occasion real public discussion.

After the ordeals of Ferguson, Bedford-Stuyvesant, Staten Island, Baltimore, and all the others, the discussion is imperative. The events of the past year have raised many questions, and one of the most important and powerful is that of history. The surprise and dismay that many people experienced—the sinking feeling that race relations in this country are in a different and much worse place than many thought—suggests that there’s no good grasp of how the U.S. got here. And so the history of race relations in the United States, including the watershed moment of 1865, has become relevant in a new and painful way.

This is what it means to live in time and history. Just as soon as there’s a feeling of certainty that the U.S. has understood and come to terms with the past, something happens that suggests the country didn’t really understand after all. So Americans are forced back upon themselves. They pick up the threads once again, hoping to gain a better understanding.

This same logic applies to the political values and ideals that measure self-knowledge and progress. U.S. democracy rests in part on a familiar tradition of political thought and aspiration. But the core elements of that tradition are not self-sustaining. They have to be engaged and reengaged, generation by generation, and fitted to the circumstances of the present day. The country can’t expect to sustain a vibrant and genuinely democratic political culture without active engagement. The tradition of democratic thought and aspiration also means engaging history. But tradition is empty, or at best abstract, if it is not attached to the concrete ways in which it has been lived, tested, and transformed over time. The democratic faith and the messy history of American democracy are two sides of the same coin.

So let us take good long look at the Second Founding. Not for the last time, certainly, but with the urgent self-reflection called for this time.