A few months ago I got a voicemail from my seven-year-old nephew informing me that he needed help building a satellite communication device. He had most of the necessary parts, he assured me, including aluminum foil, some wires and cables, and AA batteries. All we needed to get started was a radio or remote control.

Nothing came of our project, but the imaginative reach of his idea made me wonder: Where did this itch for invention come from? Was my sister sprinkling something in his cereal? Reading him Arthur C. Clarke at bedtime?