It is not so much an absence of the right theory that has thwarted attempts by physicists to understand the natural world, contends Rosen (City U. of New York), but the unacknowledged presence of deeply ingrained assumptions about the world that are essentially incompatible with the radically non-classical phenomena underlying it. He explores what might be called the metaphysics of physics, or maybe just its geometry: as the series title might suggest, topology plays a major role in the discussion.