Hand-in-hand with my grandchildren—11-year-old Lucia and 9-year-old William—I recently walked out of the Smithsonian’s National Museum of African American History and Culture in Washington, D.C., filled with gratitude and a deeper understanding of what it means to be an American. Museums hold our personal and collective histories. The photographs and artifacts, the paintings and panoramas, the documents and maps, the uniforms and tattered textiles from lives long gone not only show us where we came from, but they help us understand who we are. Although I am white, I left the African American Museum with a deepened appreciation of the fact that my understanding of myself as an American—indeed, my very identity, the sum of all the things that make me who I am—owes a great deal to the African American experience.

We began our visit in the museum basement, in the bowels of the slave ships with the shackles and sickness, recoiling at the cruelty but also bearing witness to the indomitable human spirit. My granddaughter, Lucia, was visibly moved by both the suffering and the resilience. She lingered by an exhibit of one of the oldest and most influential books written by a slave—The Interesting Narrative of the Life of Olaudah Equiano (1789). She asked her mother to take a picture of a line from the book quoted on the wall: “We are torn from our country and friends, to toil for your luxury and lust of gain.”

Equiano’s book recounts his perilous journey from a Nigerian village to the Caribbean to Virginia to England; from being sold by one slaveholder to another, to eventually buying his freedom from a Quaker; from becoming that same Quaker’s business partner to joining an abolitionist group in England. So gripping that it went through nine English-language editions in his lifetime, Equiano’s bestseller helped spur the British to pass the 1807 law abolishing the African slave trade. More than two centuries later, Equiano’s words still carry a strong punch. Lucia summarized her visit to the museum simply, “I thought the exhibits and this quote were powerful and moving.”

We ambled our way through four centuries of not only toil and trouble, but also of extraordinary achievement by African Americans in every field of human endeavor, from science, medicine, and technology to the creation of much of the most important literature, art, and music that informs our culture. The music and sports sections of the museum captured the imagination of my grandson, William. He stood mesmerized below a giant screen that streams videos of famous African American athletes. “It was impressive,” he said, “that even though African Americans suffered so much, they were determined to play sports and play music and become heroes.”

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Like my grandchildren, I was awed by the triumphs of individual African Americans—but what inspired me most was the persistent, unwavering faith of an oppressed people in the American ideal of equality, an ideal best and most famously expressed by a slave holder: “We hold these truths to be self-evident, that all men are created equal.” Year after year, decade after decade, century after century—despite very grim objective realities—African Americans held tight to the American founding rhetoric of equality and liberty. They have believed in the promise of America and, in their fights for liberty and rights and respect and dignity and equality, struggled relentlessly to realize that promise.

African Americans are not alone in treasuring the promise of America. Immigrants and refugees, representing every faith and ethnicity on earth, have fled famine, violence, political repression, religious discrimination, and economic hardship to build new lives here. Tearing themselves from families and friends, they headed for an alien shore that offered the hope of equality and opportunity. These immigrant communities, many of which have fully assimilated, have contributed enormously to our economy, politics, and culture.

As we wandered from gallery to gallery in the African American Museum, I thought about the alchemy that gives a nation its identity. The notion, popularized a century ago, of America as a “melting pot” in which various metals combine to form a durable alloy has lost credence. More recently, the metaphor of a “salad bowl”—in which different cultures retain their distinctiveness, like ingredients tossed together and splashed with oil and vinegar—has been in vogue. Pollsters and pundits crudely pigeonhole us into groups, magnifying our differences and minimizing our commonalities.

Standing in the museum’s hall highlighting African American achievements in science, medicine, and technology, it occurred to me that we are not asking ourselves the essential question: Subtract from the grand total of America the contributions of our racial, religious, and economic minorities and what would we have left? Take just one statistic: Of the 919 individuals who have been awarded Nobel Prizes, more than 40 percent have been Americans. These men and women, recognized for their consequential advances in science and their profound impact on our culture, represent every major ethnic group in the United States. Their discoveries have led to better health care, spawned new businesses, reduced poverty, and ended wars. Where would we be without them?

And behind the famous few, awarded prizes and immortalized in biographies, are the nameless legions who came to America from all over the world and put down new roots here. Their labor went into just about every farm, every road, every bridge, every mine, and every factory in this country. And they contributed to every corner of our high culture and popular culture. Who would any of us be without the richness of our music and dance, our literature and art?

I walked out of the museum thinking about the enormous debt I owe to African Americans, not only for their forced labor that fueled our economy for centuries or their incredible forbearance in the face of ongoing discrimination, but also for all the ways they have enriched our common culture. And, I thought about the debt I owe to my fellow Americans of every race, religion, and national origin who have individually and collectively created our unique American civilization. Let us not forget our national motto: E pluribus unum, out of many, one. We would not be who we are without each other.