I left the house uncharacteristically early for work one morning and stopped at my favorite cafe for a latte and a muffin. In five minutes I was back on the main road. The light turned green, and, instead of going forward, the vehicle in front of me backed into my car. I was irritated. If I had been on my usual schedule — barely on time or a bit late — I would have avoided this collision.

The other driver looked wizened, gray, and sick. “That was weird,” I said to him. “What happened?” He was flustered, and his words came out in a confusing rush of details. He was worried about the car in front of him hitting him, and he accidentally backed up too quickly, and he had cancer.