In 1879, George Darwin put forward the idea that the Moon was derived from the rocky portion of the Earth via a process of fission. He speculated that perhaps the Pacific Basin was the scar left from this ancient event. It is easy, with the hindsight gained from the discovery of seafloor spreading and plate tectonics, to look back on this idea as faintly amusing. But Darwin was doing something remarkable. He was not only speculating about the problem of lunar origin, but was looking at the modern system for evidence that betrays the mechanism of formation. In this talk, I will describe recent developments in the modern theory of lunar origin - the giant impact hypothesis - and recent attempts to forge a connection between the processes accompanying lunar formation via giant impact and the resulting dynamical and isotopic signatures observable in the modern Earth-Moon system.