One evening, I spent the evening at a laundromat with a homeless friend whose clothes required extra detergent. She carries most of them in a large tote, so we washed every piece of clothing she owed. Once I dropped the quarters inside and poured powdered soap into the washer, I warned the couple sitting by the wall with their tiny in fant that if suds seeped from the washer, it was my fault. I didn’t measure the amount needed and guessed how much to pour.

I engaged in further talks with this c...