This volume brings together a number of original articles by leading Leibniz scholars to address the meaning and significance of Leibniz's notions of compossibility and possible worlds. In order to avoid the conclusion that everything that exists is necessary, or that all possibles are actual, as Spinoza held, Leibniz argued that not all possible substances are compossible, that is, capable of coexisting. In Leibniz's view, the compossibility relation divides all possible substances into disjoint sets, each of which constitutes a possible world, or a way that God might have created things....