 Leaving aside questions about ontology, there is a distinct—or at least potentially distinct—issue regarding space and time: what is the origin of our representation of space and of time? This third issue arises from the sense in the early modern period that our idea or representation of space and time must somehow be importantly distinct from our idea or representation of ordinary physical objects. Many believed that space and time are causally inert and therefore imperceptible—how then are we are able to represent space and time at all? Few are willing to deny that we have a representation, not merely of spatial and of temporal objects, but also of space and time themselves, so there is a genuine puzzle lurking here.