On the day she died, I set my phone’s wallpaper to my favorite photo of Peggy—appearing to smile on a ridgeline trail in Missoula, Montana, the bright-yellow balsamroot flowers in bloom behind her. But a month later, I told myself that it was time to stop wallowing. Instead of a memorial photo of Peggy, I opted to try a newer, “dynamic” wallpaper feature called “Photo Shuffle.” Every so often, my iPhone would change my wallpaper and home screen to an image it had grabbed from my camera roll. To help it along, I could offer parameters for the photo choice. Knowing that Apple’s Photos app uses image-recognition software to identify cats and dogs in the camera roll, I chose a “Pets” filter.

Over the months, Hank and I built gentle three-mile jaunts in the Fells into rugged five-mile loops and eventually technical eight-mile circuits. The sound of my feet scraping across hardened dirt, the clinking of Hank’s tags, and the breath filling my ears, soon grew into a chorus that began, little by little, to drown out the cacophony of guilt, rage, and failure that kept me company.