Adorno placed "almost unlimited trust in finished teachings, in Marxism, psychoanalysis, and the teachings of the Second Viennese School." Hegel Adorno's adoption of Hegelian philosophy can be traced back to his inaugural lecture in 1931, in which he postulated: "only dialectically does philosophical interpretation seem possible to me" (Gesammelte Schriften 1: 338). Hegel rejected the idea of separating methods and content, because thinking is always thinking of something; dialectics for him is "the comprehended movement of the object itself." Like Gerhard Schweppenhäuser, Adorno adopted this claim as his own, and based his thinking on one of the Hegelian basic categories, the determinate negation, according to which something is not abstractly negated and dissolved into zero, but is preserved in a new, richer concept through its opposite. Adorno understood his Three Studies of Hegel as "preparation of a changed definition of dialectics" and that they stop "where the start should be" (Gesammelte Schriften 5: 249 f.). Adorno dedicated himself to this task in one of his later major works, the Negative Dialectics (1966). The title expresses "tradition and rebellion in equal measure." Drawing from Hegelian reason's speculative dialectic, Adorno developed his own "negative" dialectic of the "non-identical." Karl Marx Marx's Critique of Political Economy clearly shaped Adorno's thinking. As described by Jürgen Habermas, Marxist critique is, for Adorno, a "silent orthodoxy, whose categories [are revealed] in Adorno's cultural critique, although their influence is not explicitly named." Marx's influence on Adorno first came by way of György Lukács's History and Class Consciousness (Geschichte und Klassenbewußtsein); from this text, Adorno took the Marxist categories of commodity fetishism and reification. These are closely related to Adorno's concept of trade, which stands in the center of his philosophy, not exclusively restricted to economic theory. Adorno's "exchange society" (Tauschgesellschaft), with its "insatiable and destructive appetite for expansion," is easily decoded as a description of capitalism. Furthermore, the Marxist concept of ideology is central for Adorno. Class theory, which appears less frequently in Adorno's work, also has its origins in Marxist thinking. Adorno made explicit reference to class in two of his texts: the first, the subchapter "Classes and Strata" (Klassen und Schichten), from his Introduction to the Sociology of Music; the second, an unpublished 1942 essay, "Reflections on Class Theory", published postmortem in his Collected Works. Sigmund Freud Psychoanalysis is a constitutive element of critical theory. Adorno read Sigmund Freud's work early on, although, unlike Horkheimer,