 This approach to answering fundamental metaphysical questions by casting into doubt the traditional distinction between ontology and epistemology not only leads to a different conception of what idealism is all about. Above all, it means that one has to sketch out the difference between idealism and whatever is taken to be its opposite (realism, naturalism, materialism, sensualism etc.) not in terms of different kinds of “stuff” either material or mental but to turn away from any “matter” whatsoever. Rather, idealism is now defined in terms of the opposition between dynamic elements like activities and forces as the primary constituents of reality and more substantial items like material objects and (spiritual) persons. Idealism understood in this fashion becomes the name of a “metaphysical” (in a non-traditional sense) world-view that is opposed to what especially Fichte and Schelling liked to call “dogmatism” and is rooted in assumptions about dynamic processes that are operative in the course of self- and object-constitution. There is thus a fundamental difference between the idealism of German idealism and the immaterialism of Berkeley: where Berkeley’s idealism focused on ideas as the “stuff” of existence and assumed minds, whether human or divine, as their repository, the German idealists focused on the mind as active and largely tried to suppress the traditional ontology of substances and their accidents within which Berkeley still worked, which Hume questioned but for which he supplied no alternative, and which Kant again defended by conceiving of substance and accident as relational categories.