This is the first modern interpretation of Leibniz's comprehensive critique of Locke, the New Essays on Human Understanding. Arguing that the New Essays is controlled by the overriding purpose of refuting Locke's alleged materialism, Jolley establishes the metaphysical and theological motivation of the work on the basis of unpublished correspondence and manuscript material. He also shows the relevance of Leibniz's views to contemporary debates over innate ideas, personal identity, and natural kinds.