The other morning, as I drove home from a ridiculously early-morning class that I teach, I caught my neighbor, June, crossing the street in her robe and slippers.

“What are you doing?” I asked.

“Oh, I’m just going to put Betty’s newspaper on her porch.”

I knew the answer already, because I see it from my window sometimes. June scoops up Betty’s newspaper and drops it on her porch. The next day, here comes Betty across the street in her robe to do the same thing for June. They wrestle each ot...