Jay Kolsch for The New York Times Supported by By Sterry Butcher Sterry Butcher is a writer in Marfa, Texas, where she lives on a farm with horses and donkeys. Horses are exquisite machines.

Mules, hybrids of donkeys and horses, inherit strength and resilience from both parents, making them valuable work animals. Ponies, a subset of horses bred for their small size, exhibit strength ...