Refractive materials give limited control of light: we can fashion lenses, and construct waveguides, but complete control is beyond simple refracting materials. Ideally we might wish to channel and direct light as we please just as we might divert the flow of a fluid. Manipulation of Maxwell’s equation shows that we can achieve just that and metamaterials open the door to this new design paradigm for optics, providing the properties required to give complete control of light. One potential application would be to steer light around a hidden region, creating a cloak of invisibility.