 Conway’s case for substance monism rests on fundamental principles of her metaphysics: it is grounded first in her vitalist conception of all being. On the principle of similitude whereby all things bear some resemblance to God, everything in existence must be in some sense alive—from God down through angels, to human beings, animals, plants and mere dust. There are of course other attributes of created things not shared by God (mutability, shape or “figure” and solidity or density). Also, creatures, unlike God, are multiple and subject to time. Since all substance created by God must be living, it follows there can be no non-living substance. Furthermore, matter being nothing but inert extension (“dead” is Conway’s adjective) is devoid of likeness to God, so cannot exist. It follows that body and soul (or spirit) are not distinct substances, but different gradations or modes of the same substance. Secondly, all created things are subject to change, and change is only possible between things that are alike. This holds both for divine causality and change within created nature. The main limit to change is ontological: creatures may change radically, but not to the extent that they might lose any of their essential properties, or acquire others, for that would entail change of substance. It follows, therefore, that within the ontological parameters of the third species, all changes are changes of degree or mode, not substance.