Nathaniel P. Morris is a student at Harvard Medical School.

My girlfriend recently moved into a new apartment in New York City, and I took a train down from Boston to lend a hand. We spent most of the weekend arranging furniture and unpacking her things, but we also caught up with college friends. Over dinner, we chatted about work, family, relationships and politics. I had heard about Mayor Bill de Blasio and his vision to combat inequality. I didn’t know that we were about glimpse his Tale of Two Cities.

On Sunday, after some shopping and a walk through Central Park, we decided to get out of the cold. We descended into the subway at Grand Central Station to head back downtown. When the train rolled up, we snagged a pair of seats, two of roughly 20 passengers in the car. None of us said anything as we creaked into the dark tunnel.

A few stops passed in relative silence as the train rumbled along. A teenager bobbed his head, music faintly emanating from his oversize headphones. We reached Bleecker Street, and no one seemed to be getting on or off. Then, just as the doors were about to shut, a disheveled man wearing glasses and a backpack stepped aboard. Towering over us, he began to shout.

“Excuse me, ladies and gentlemen. I apologize for the inconvenience.”

Everyone looked up.

“I lost my job a few months ago and have been living in a homeless shelter.”

Everyone looked down.

“They put a roof over my head, but I still have to find my own food. I haven’t had a bite to eat all day, and I haven’t had any luck on these trains. I’d really appreciate some loose change or extra snacks, any kind of help.”

When he finished his speech, the man pulled out a shiny little bag, the kind most people use for gifts. He walked through the car, rattling his receptacle in front of person after person — rows of slumped heads, a ritual of somber neglect. Many people pulled the trick of taking out their cellphones and pretending to do something important. I opted for starting a random conversation with my girlfriend — as if the desolation before us couldn’t be seen or heard, so it wasn’t our fault for not helping out. The well-dressed couple across from us had three bags of groceries from Trader Joe’s. The man shuffled by with a longing gaze, but no success.

When he finally reached the end of the car, he cried out, “See, I told you I was having bad luck.” He slumped into a seat, closed his eyes and buried his head in his hands.

For the next couple of stops, I periodically looked over at him. I thought about why I didn’t give him anything when I knew my girlfriend and I didn’t really need the cash in our pockets. I went through the usual justifications: Maybe he’s an alcoholic or on drugs. Perhaps he’s a criminal who got fired. Why does this guy deserve others’ money and assistance, just for begging? Wouldn’t my money go further at a homeless outreach program or an organized charity?

Then I thought about the sheer desperation, and courage, it takes to stand in front of a train of strangers and bare your soul, announcing to everyone the shambles your life has become and hoping for scraps in return. I guess that the anxiety of the whole situation is why I just waited for the moment to pass.

Suddenly, the train screeched to a halt. We were at City Hall. The man slowly stood up, looked down the car one last time and left. I watched through the scratched window to see if he would move on to the next car. Instead, he walked up the stairs, empty-handed, into the cold night.