"You put the cotton in here," the museum guide said, pointing to one side of a small machine. His small model of the cotton gin picked up the bolls of raw cotton and pulled them across rows of wire teeth. The hard, prickly seeds dropped out, leaving only the useful fibers from the cotton. Like many innovators, Eli Whitney saw a technical problem. Apart from the coastal areas, the farms of the American South couldn't grow the profitable long-staple cotton. They could only produce a short-staple variety, with tough seeds that took hours of painstaking labor to remove. Whitney's cotton gin solved the problem, making cotton farming more effective and profitable.

But the display in front of me was not about the wonder of human ingenuity. It was about the tragedy of slavery. I saw the cotton gin in action at the National Underground Railroad Musuem in Cincinnatti, Ohio, and what our guide wanted us to understand was that the cotton gin helped expand the cotton plantations of the South and created a huge new market for slave labor. Planters didn't need laborers to pick out cotton seeds, but they did need a huge work force to plant and pick the cotton that they fed into Whitney's amazing new machine.

How a machine is created and used matters as much as what it does. For us, it matters where the metals for our electronics are mined, and who puts them together, and who really benefits from the amazing features of our latest toys.