 Strictly speaking, Conway’s metaphysics is an ontology of three kinds of being, which she calls “species”. Each of these is a single substance distinguished by a particular set of properties which determine its essence, and set its ontological boundaries. Conway holds that there can only be three species, and one species cannot transform into another. The species are nevertheless inter-connected through their shared properties (principally the “communicable” attributes of God), and differentiated by others (principally mutability which is a property of the second and third species). The second species (Christ or Middle nature) is differentiated from both God and other created things because it also retains God’s immutability. As a causal intermediary between God and Created Nature, Middle nature is analogous to Cudworth’s Plastic Nature and More’s Spirit of Nature, but a divinized version.