I ride the Metro to work every day, and Monday I was late. Well, it wasn’t so much that I was late as the train was late. The car was jammed with people — some squished in seats with their noses in newspapers or books or zoning out on their iPods, while others crammed into the aisles staring into space and trying to stay upright.

We stopped at a station, the doors opened and a few people boarded. The doors closed and we began moving again when a man’s voice somewhere behind me said pleasantly, “Good morning. Excuse me.”

And he began to sing.

A lovely tenor voice filled the car. It had an accent — Middle Eastern or Indian or maybe Caribbean, I don’t know because I never saw the man. And he wasn’t singing just any song.

He regaled us with at least three verses of “O Come, O Come Emmanuel.”

The car was silent during his little recital. Most people continued reading their papers. When he finished there was a smattering of applause, and he said, “Everyone have a blessed day.” As if he’d timed it to the second, the train stopped then, the doors opened and he left.

I never saw my little Advent songbird, but I appreciated his tune. On a day when things weren’t going according to plan, that brief musical interlude improved my mood.

I was also heartened by the reaction of my fellow passengers. No one booed this man or shouted him down or told him to be quiet. No one grumbled about his breaking what seems like the unspoken rule of silence on the Metro in the morning.

Rather, they let him share his faith with a captive audience, and then go on his way. He may never know the effect his song had on his listeners that morning, but isn’t that what evangelization is all about?