Abstract: Argues that later developments in Leibniz's thinking about the relation between perfection and existence provide a more promising basis for a version of his ontological argument for theism – a version that is substantively metaphysical rather than purely logical in nature. These developments involve viewing existence not as one of the qualities into which an essence may be analyzed, but as entailing a higher-order property or status that an essence may have. The revised argument rests on a strong form of the principle of sufficient reason and on the thesis that a bias in favor of existence is built into the foundations of ontology.

Keywords: essence, existence, higher-order property, Leibniz, ontological argument, perfection, qualities, sufficient reason,