 The passage from the Inaugural Dissertation hints at five distinct questions or issues concerning space and time. First, there is the question of the ontology of space and time considered within the framework of what Kant would regard as the dogmatic metaphysics of the seventeenth century. This framework might suggest that if space and time are to exist, or to characterize the physical world, they must be considered either substances in their own right, or else properties of some substance. Neither option seems particularly attractive. Space and time seem distinct from substances because they are causally inert, causally inaccessible—their aspects or properties cannot be altered by interacting with any other substance—and imperceptible. Since they are often regarded as infinite, moreover, some thinkers have doubted that they could be substances, as God is often thought of as the sole infinite substance (Descartes may have conceived of space as “indefinite” for this reason). However, it is also difficult to think of space and time as properties of any substance, for then they would presumably be dependent on that substance for their existence. If we regard them as dependent on any contingent substance, it seems that we would be committed to the idea that space and time could fail to exist, or could disappear, depending on the happenings of that contingent substance. One might think instead that space and time depend on the one necessary substance, but this obviously raises a host of other issues. To think of space and time as properties of God is potentially to regard God as spatiotemporal, which is verboten from the point of view of many seventeenth-century thinkers (Janiak 2008, chapter five).