My dissertation is about two traditional metaphysical problems and how these shape the philosophies of Leibniz, Kant, and Hegel. The problems concern the nature of individuals and individuation, and the nature and ontological status of opposition. The question of individuation asks, "What makes some thing, A, the very thing that it is, and no other?" The related topic of opposition is about whether or not a combination of positive qualities can produce a negation of qualities. I argue that these two problems are central to the subject matter of the second book of Hegel's Science of Logic , the "Doctrine of Essence," and that Hegel's response to these problems illustrates more generally his relationship to Leibniz and Kant, for whom the problems are also central. Specifically, I claim that Hegel's reflection on these topics guides the dialectic of the first division of the "Doctrine of Essence," "Essence as Reflection in Itself," towards its conclusion in Hegel's holism about the relation between substance and property, on the one hand, and between properties generally on the other. I claim that Hegel's holism on these two points, and the dynamic ontology of particulars they support, results from his criticisms of two key Leibnizian doctrines— the principle of the identity of indiscernibles and the principle that all reality is in agreement—but that these criticisms do not lead Hegel to abandon metaphysics as a philosophical program. Hegel's assessment of Leibnizian rationalism is thus quite distinct from Kant's critical evaluation of it in the "Amphiboly of the concepts of reflection through the confusion of the empirical use of the understanding with the transcendental." Hegel accepts Kant's criticism that Leibniz confounds the comparison of concepts with the comparison of objects thought under those concepts, but he distances himself from Kant's thesis that this criticism presupposes a radical distinction between sensibility and understanding. Against Kant, Hegel demonstrates that Leibniz's metaphysics fails on conceptual grounds alone, i.e. before it is submitted to "transcendental reflection." Hegel thus shows another way forward in post-Kantian philosophy, one that remains thoroughly metaphysical in its orientation and conclusions.