I went to the hardware store to look at lawnmowers. Ours was getting more than a little old. I’d asked Emma if she wanted to come along, and she said she had a few things at home she needed to get done.

The lawnmowers were nice, but expensive. I decided my trusty old lawnmower might last another season. Just as I was getting in the car to head home, I got a text from Emma asking me when she could expect me. “Five or ten minutes,” I texted back. “Can you pin it down more?” she said. “Seven minutes and thirty-seven seconds,” I said. “Good,” she said. I checked the time on my cellphone. I set the timer for seven minutes. In the driveway the elapsed time was six minutes and twelve seconds. At seven minutes the timer went off and I got out of the car. Twelve hippopotamuses later I opened the front door.