The opening day of the National Museum of African American History and Culture on Sept. 24. (Marvin Joseph/The Washington Post)

As we near the end of Black History Month, I would like to share a recent experience I had while visiting the District. After a December business meeting, I decided to walk over to the National Gallery to visit a favorite exhibit. On the way over, I passed the newly constructed Smithsonian National Museum of African American History and Culture, which was still under construction when I moved from the D.C. area to Boston.

The building itself is incredible, and walking by I thought: Stop here instead. It was late in the afternoon, and the crowds I saw when flying over the museum that morning had mostly dissipated. I made my way up to what appeared to be the tour entrance and was met by a security guard standing outside.

“You need a ticket,” he said, “I knew you didn’t have one; it was written on your face as you stared up at the building standing out there.”

“Oh,” I sheepishly responded. “I’m very sorry. I had no idea. Have a nice….”

“Tell me something that happened between 1400 and 2008,” he said.

“I’m sorry?” I replied, somewhat bewildered.

“Tell me something that happened between 1400 and 2008,” he repeated in the same direct tone.

Unsure of how to respond, I blurted out the safest answer I could think of standing on the Mall in the shadow of the Washington Monument: “the American Revolution.”

“Okay, here you go,” he said, removing a ticket from his pocket. He handed it to me, broke off the stub, and said, “Hide that in your pocket and don’t show it to the people inside.”

Those who have visited Washington know that the Smithsonian Museums do not require an admission fee. Tickets may be granted on occasion for special events, but generally the doors are open and there is little fuss. I appreciated the guard allowing me in the tour entrance and, at the time, thought he simply saved me the trouble of having to walk around to the front of the building. I thanked him and made my way inside.

I don’t want to spoil any surprises for readers who have yet to visit the museum, but it so powerfully conveys the message of freedom that visiting should be a national requirement. I stayed until closing.

When leaving, I made my way over to the tour entrance to thank the guard again for the ticket, but he had left. As soon as I stepped through the door outside I heard in a booming, familiar voice on speakers emanating from the South Lawn “5-4-3-2-1” to mass applause. The White House Christmas Tree suddenly sparkled in the distance.

After mysteriously gaining admission to a newly built Smithsonian Museum about African Americans, I heard our first black president count down his final Christmas tree ceremony before the door of the museum closed behind me.

Later that night, I was telling some local friends about the museum, but before going into any detail they unanimously interrupted and asked with amazement: “But how did you get in? Tickets aren’t available for months.”

Only then did I realize the incredible gesture made by the enigmatic security guard.

I’m a white guy who grew up in suburban New England, and when standing outside the building earlier that afternoon in my tweed blazer, I probably looked like a white guy who grew up in suburban New England. I’ve known very little hardship in my life and have never, ever felt mistreated or systematically disenfranchised.

A lot happened between the years between 1400 and 2008, which just so happen to be the precise years surveyed in the historical section of the museum. Many answers could have been given to his mysterious question — some good, but most bad.

When Dave Chappelle hosted “Saturday Night Live” after the election, he closed his monologue describing a dinner with BET at the White House. Everybody at the White House that evening (apart from Bradley Cooper, he joked) was black. He concluded by saying that he is going to give Donald Trump a chance, and he hopes that President Trump gives him a chance too.

So, I write this to say thank you. Not to the architects and builders of the museum responsible for its external construction, or to the curators and experts responsible for its internal construction, or even President Obama for being a piece of that construction, though they all played a necessary and important role. Instead I write this to say thank you to the security guard, not for the simple gesture of handing me a ticket, but for the far more profound gesture of giving me a chance.

Let’s ensure he’s given a ticket, and chance, too.

Ryan Stelzer, co-founder of Strategy of Mind, a global leadership and team development firm, was a presidential management fellow in the Obama administration and a former special assistant to the chairman of the Export-Import Bank of the United States.