And then I understood: to me, it was a question of scale. If I were the size of a microbe, a human body would seem like a huge city of individuals. On the next level, Isaac and I had wanted to travel to the Trembling Giant in Utah, which looks like an aspen forest with tens of thousands of trees but is in fact one single plant born eighty thousand years ago, connected at the roots. On the next level, maybe all humanity looked like the cooperating fungus cells, cooperating to strip, heat, and destroy the Earth.

I smiled. I didn’t know if Isaac would understand this, or tear it apart with his reasonableness, but it didn’t matter—“Cooperation is more important than competition,” I said to Dice, his words, and he said, “Exactly.”

I was relieved, forgetting, for a moment, the slaughter.

Dice picked up the largest of my lambs. He calmed her, scratching around her ears as though she were a barn cat. “Best to take them out of view of the mothers,” he said. He carried her across the field to the edge of the woods, where he’d set up a pallet and hay, a steel frame and a pneumatic machine. I could barely breathe. My guts had dropped into my feet, and my hands shook.

He laid the lamb on her side and took out a long straight knife, which he handed to me. “You have to cut her cleanly,” he said, “confidently, or it’s inhumane.” He rubbed his thumb against his lip, like he was trying to press his words in—a gesture I’d learn to recognize.

He held the lamb’s head back. She bayed. She flicked her ears. Her gold eyes rolled at the winter fields.

I remembered how good I became at running and leaping and throwing myself back over the pole. Isaac had taught me to be fearless, but that day with Dice on the edge of the woods, I was not. I suppose I stood there for a minute or two, with my hands shaking, what seemed like hours as I felt his opinion of me blacken and curl into cinders. He took the knife from my hand.

Efficiently, and, it seemed, regretfully, he cut her throat, then pushed her head all the way back.

I turned away, and saw the three dogs coming up through the woods. Dice chopped off the lamb’s hooves and tossed them to the dogs, then hung the carcass up on his steel rack. “The first rule of farming is ‘Don’t get attached,’ ” he said.

He brought over the machine and shoved a sharp tube that jetted air in between the lamb’s muscle and skin, so that she momentarily ballooned up white and cartoonish. Then he hung the lamb up again and began to skin her. Her costume draped on the ground while he cut off her ear and carefully peeled the downy wool from her face.