 Wolff’s way of classifying a philosophical system was enormously influential in eighteenth-century Continental philosophy—for example, it was closely followed by Alexander Gottlieb Baumgarten in his 1739 Metaphysica, which was in turn used by Kant as the textbook for his metaphysics (and anthropology) lectures throughout his career, and whose definition of dogmatic idealism, as contrasted to his own “transcendental” or “critical” idealism, would also be that it is the position according to which there are only minds—and so it is no surprise that almost all talk about idealism was heavily influenced by Wolff’s characterization. This is so because it reflects the main metaphysical disputes in seventeenth- and early eighteenth-century philosophy on the Continent quite well. In terms of Wolff’s distinctions, these disputes can be framed as disputes between (a) monists and dualists and (b) idealists and materialists; positions in this debate were often influenced by perplexities surrounding the (ontological) question of the interaction of substances, although they were also influenced by the (epistemological) debate over innatism. Although neither dualism, whose main representative was Descartes (who asserted the existence of both res cogitans and res extensa), nor monism, allegedly though debatably represented by Spinoza in its materialistic version (substantia, deus, natura) and by Leibniz in its idealistic form (monad, entelechy, simple substance) succeeded in finding satisfying answers to this and related questions, in the early modern era these disputes shaped the conception of what the object of metaphysics (metaphysica generalis sive ontologia) was supposed to be.