If you have spent any time at all on YouTube, you have probably seen videos of people hearing for the first time or people seeing color for the first time—videos of people who, through the miracles of modern science, have senses restored that had either been missing altogether or that had become dull through illness or accidents. It is hard not to be moved as a child hears her mother’s voice for the first time or to be thrilled as a man gets his first glimpse of the world in color