We all hummed a song nobody knew during the power cut

The power went out in a block of the Loop at lunchtime on a Wednesday and hundreds of us ended up on the pavement saying nothing, looking at our phones, then at each other. A man began to hum. Someone joined in. Nobody knew the song but we all hummed it. It lasted fifteen minutes. When the lights came back we clapped, and went back to our desks, and I did not see any of them again. I still hum it sometimes at that corner.