This essay focuses on an intriguing cycle in early modern ontology – that is, in the early modern study of what exists. René Descartes helped to usher in a new era in ontology by putting pressure on the causal powers posited by his scholastic forbearers. Nicholas Malebranche went a step further in flatly denying the existence of created causal powers. Gottfried Wilhelm Leibniz, however, demurred, arguing for a return once again of causal powers. Having explored the decline, fall, and rise of causal powers in the ontologies of Descartes, Malebranche, and Leibniz, the essay closes by asking if early modern debates over causal powers might have anything to teach us about the study of ontology itself.