President Obama, first lady Michelle Obama and Ruth Odom Bonner, center, ring the bell opening the Smithsonian National Museum of African American History and Culture on Saturday. (Manuel Balce Ceneta/Associated Press)

After 99-year-old Ruth Odom Bonner, whose father was born into slavery, helped ring the bell that opened the National Museum of African American History and Culture on Saturday, it was hard to be in a sea of people. On the Mall, only a few blocks from the museum, they were playing Frisbee. A dog scampered between two people who seemed to know each other. America was in shorts and flip-flops, grazing from food trucks, lolling on the lawn, taking selfies. Something solemn, momentous, perhaps even transformative had just happened, and the president of the United States had spoken some of the simplest but most powerful words of his presidency: “We’re not a burden on America, or a stain on America, or an object of pity or charity for America. We’re America.”

I wanted to preserve the sound of those bells in my head, as if they really did signify the end of our historical amnesia about the origins of the United States, the source of its wealth, the arc of its theft, the history of its injustice, the segregation not just of its people, but also of meaning, emotion, dreams, hope and so much else that is fundamental to being human. So I ducked into the National Gallery of Art, where the crowds were thinner. On the ground floor was an oversize photograph by the African American artist Hank Willis Thomas. It shows two black men, shirtless, playing basketball. Above them dangles a noose.

Photographer Hank Wills Thomas’s “And One” (2011). (Courtesy of the National Gallery of Art/Copyright Hank Willis Thomas)

The Thomas photograph crystallized a wariness I had been feeling throughout the festivity of the day. The artist uses the slick production values and visual condensation of advertising to make some of the most jarring images in circulation today. A favorite target is corporate America’s embrace, and exploitation, of African Americans, through the subtle manipulation of ideas of aspiration, affirmation and inclusion. In this image, “And One,” the noose functions as the basketball hoop, and one player clearly has his eye on it. Is he focused on the goal of the game? Or does he watch it nervously? Does opening this new institution mean game over when it comes to the struggle for a place at the table? Or is the museum — its purpose, its message, how it is used and interpreted — something we must keep our eye on?

On Saturday, the picture also seemed to do something simpler and more poetic, echoing the ambivalence heard in many of the speeches before the museum’s doors were opened.

The president said, “A museum alone will not alleviate poverty in every inner city or every rural hamlet. It won’t eliminate gun violence from all our neighborhoods, or immediately ensure that justice is always colorblind.” In the weeks leading up to the opening of the museum, others noted that the president embodies this American ambivalence: His election did not usher in a post-racial society and, in some quarters, has inflamed the still volatile embers of hatred.

Throughout the emotional celebrations, I felt presentiments of wariness even in the structure of the museum. Architect David Adjaye, of the Freelon Adjaye Bond/SmithGroup team that designed the museum, has described it as a “monitor” on the Mall, a building that doesn’t just select and frame beautiful views of its iconic neighbors, but also watches them with the eagle eye of surveillance. One critic has compared the cuts through the building’s aluminum-paneled “corona” to the angle slits cut into the defense wall of an old fortress.

Perhaps that takes the analogy too far, but the corona, which shields the glass box of the museum’s interior from light, obstructing or filtering views, is easily read as a gesture of ambivalence: It defends the interior and refuses to reward outsiders looking in with any certain knowledge of what it contains. History, it proclaims, is not transparently available to mere spectators.

I am wary for several reasons. A quarter century ago, the Smithsonian’s American Art Museum opened an exhibition that, according to its catalogue, promised to highlight the gulf “between the alarming facts of history and the loudly proclaimed ideals of progress.” It was devoted to the art of the American West — the cowboy-and-Indian narratives and romanticized landscapes — and cast a skeptical eye on all of that. The exhibition quickly ran afoul of many critics, and Congress, and about a month after it opened, the museum revised it. (This kind of scandal seems to happen about twice a decade at the Smithsonian.)

The African American Museum, so long in coming, so desperately needed, is ultimately a Smithsonian museum, and the Institution has a checkered reputation when it comes to defending the integrity and independence of its scholarship and museums.

The new museum opens with all the usual tensions already in place. Among its major donors are banks that played a brutal role in predatory loan scandals that targeted African American communities as well as companies that manufacture the cigarettes, food and soft drinks that play such a big part in the plague of diabetes and other health issues that afflict the black population. This doesn’t mean that the museum can’t be independent, or that the scholars and curators who created the exhibitions were in any way compromised by pressure. But it does mean that it could take substantial fortitude to, say, mount an exhibition about racism and professional sports when one of museum’s major funders is the NFL. In the age of the modern, mass-market museum, freedom and independence are never a given; they must be reasserted and defended with every new exhibition.

A peek at the Mall’s latest addition

The museum’s opening ceremony Saturday did indeed feel like “a mini-inaugural,” to borrow the words of its founding director, Lonnie G. Bunch III. But that spectacle of power, thick with politicians celebrating a symbolic milestone while failing to act on real crises that add to the danger and disadvantage of being African American, only adds to the wariness we should feel.

Symbols are important, and the symbolic power of the new museum is extraordinary, necessary and, one hopes, a fundamental “reframing” of American history, to borrow Obama’s term. It still has a formidable climb to convince much of America that there is a complexity and trauma in our history not easily encompassed by the old history books. But now it is Day Two, and we face the reality that not only is this building an extraordinary symbol, but it also marks the emergence of a new institution built by a new establishment and subject to all the stresses and strains that establishment museums have always faced. What are the narrative tropes, the emotional metaphors, the ideas borrowed from poetry, religion and popular culture, the myths that comfort, the cliches that obscure, that will make it difficult for this new museum to tell “the unvarnished truth”? What power will it serve? How will it self-censor?

These are the questions that every museum — no matter its subject, no matter its audience, no matter who built it — must face. The bells Saturday were deeply moving, perhaps because we have traditionally rung bells not just in celebration, and in mourning, but also as a warning. A new museum has opened, and it is a historic milestone. And now we owe it this honor: to watch it very carefully and hold it to the highest standards, because no matter how unrealistically high our expectations for it are, it is now a museum just like any other.