Dear Diary:

One early spring morning in Manhattan several years ago, I decided to treat myself to a trip to the Metropolitan Museum of Art. I was looking forward to a quiet Sunday. When I boarded the subway at Chambers Street, I was relieved to find myself alone in the car.

My happiness was short-lived. At Spring Street, a noisy bunch of high-schoolers wearing enormous day packs flooded in, chatting, shoving one another, and plugging away on their electronic devices. I sighed. Why my car? Why couldn’t my morning have just a little more peace and quiet?

Then, without warning, I heard a high-pitched whistle. It took me a minute to place the sound: a pitch pipe. I looked up. The students began to sing — the “Kyrie Eleison” from Mozart’s “Requiem.” I was entranced.

They continued singing, conducting one another with their eyes, all the way up to my stop.