This volume explores the unity of logic, epistemology and ontology in Hegel's dialectic and the interrelation among the three, thereby revealing the internal features of Hegel's dialectic as well as the connection and divergence between Hegel's and Marx's philosophical thought. As the final volume of a three-volume set that gives insights into Hegel's dialectic and his overall philosophical thought, the book analyzes Hegel's dialectic as "a unity of three." As logic, it transcends language and is therefore epistemology; as epistemology, it transcends theory and is therefore ontology; as ontology, it transcends existing things and is therefore logic. Hegel's dialectic thus demonstrates itself as the revolutionary development of each of these three fields in the history of Western philosophy. The principle of the agreement of logic with history thereby expressed immediately becomes one of the most important philosophical sources of inspiration for Marx's historical materialism. A more profound understanding of Hegel's philosophy will therefore deepen our understanding of the philosophy of Marxism. The title will appeal to scholars and students interested in Hegel's and Marx's philosophy, German classical philosophy and Western philosophy.