The thought determinations of Book 1 lead eventually into those of Book 2, The Doctrine of Essence. Naturally the logical structures and processes implicit in essence-thinking are more developed than those of being-thinking. Crucially, the contrasting pair essence and appearance of Essence-logic allow the thought of some underlying reality that manifests itself through a different overlying appearance, in the way that the forces posited by the operations of the Understanding (explored in the Phenomenology’s Chapter 3) are grasped through the appearances they explain. In contrast, the categories of Being-logic seem to govern thought processes that are restricted to qualitative phenomena and their co-ordinations. But distinction between essence and appearance must itself instantiate the relation of determinate negation, and the metaphysical tendency to think of reality as made up of some underlying substrates in contrast to the superficial appearances will itself come to grief with the discovery that the notion of an essence is only meaningful in virtue of the appearance that it is meant to explain away. (In terms of the ultimate conceptual categories of singularity, particularity and universality, this discovery would be equivalent to grasping the idea that the singularity of the underlying, non-perceivable substrate or substantial form is meaningful only in relation to something that can bear the particular qualities that constitutes its worldly appearance.) For Hegel it is the complex modern, but pre-Kantian, versions of substance metaphysics, like those of Spinoza and Leibniz, that bring out in the most developed way the inherently contradictory nature of this form of thought.