 If one regards space (like time) as existing independently of all objects and all possible relations, and yet one admits that space is causally inert and imperceptible, as one presumably must in the late eighteenth century, then one is committed to the idea that there is a kind of infinite and eternal non-entity in the world. Space is a kind of non-entity, Kant suggests, because on the one hand it is said to exist independently of everything else, and yet on the other hand, it is said to be causally inert and imperceptible, which would distinguish it from every other sort of thing that exists. Kant simply cannot stomach this metaphysically preposterous notion. It is therefore incumbent upon him to develop a theory of space (and of motion) that meets at least two distinct criteria: (1) it coheres with his understanding of the theory of universal gravity, and of what he regards as its implication, viz. that gravity is an essential feature of material bodies; and, (2) it avoids the metaphysically problematic aspects of Newtonian absolute space. Kant tackles precisely these tasks in the Metaphysical Foundations, which was published in between the appearance of the first and second edition of the Critique, arguing that we can regard absolute space as a kind of idea of reason, an ideal that we approach asymptotically in our theorizing about motion. Absolute space is therefore nothing more than a kind of ideal within our philosophy, and no longer a harmful aspect of our ontology.