He had been learning how humans transform reality into ideas—and then use those ideas to build a new reality.… On a rainy Saturday morning in Kyoto, six-year-old Ren stood in the kitchen doorway and watched his father repair a broken drawer. His father had spread a screwdriver, measuring tape, screws, and a small electric drill across the floor. Ren watched carefully. The drill whirred. The screwdriver turned. The measuring tape snapped back with a satisfying metallic sound. “Almost done,” his father said. Ren wanted to help. He reached for the screwdriver, but his father gently moved it away. “Not yet. It can be dangerous.” Ren frowned. He understood the warning, but that did not make the desire disappear. For several minutes, he simply watched. Then he disappeared into his room. His father assumed he had lost interest. He hadn’t. Ren returned carrying a wooden ruler, three pieces of building blocks, a plastic cup, an...