It has become a commonplace of criticism to refer to Mann as an 'intellectual novelist', and certainly Mann himself did nothing to discourage the view that he was a philosophical novelist whose works incorporate a vast body of German thought. In the first of his 'Letters from Germany' published in The Dial in November 1922, he spoke of the rise of a type of book he dubbed the 'intellectual novel', but the examples he cited were not exactly works of fiction: Count Hermann Keyserling's Travel Diary of a Philosopher (1919), Ernst Bertram's philosophical study, Friedrich Nietzsche: An Attempt at a Mythology (1918), and Friedrich Gundolf's monumental biography of Goethe (1916), not to mention Spengler's Decline of the West (1918-22) (xiii, 265). Clearly, Mann's novels belong to a rather different category from these texts (although they all have one thing in common - length). This chapter examines Mann's knowledge of major German thinkers and writers, his use of those figures in his novels and essays, and the way their ideas form part of his 'intellectual world'. Beginning with Mann's early fascination with Schopenhauer, Nietzsche, and Wagner, I go on to investigate his reinterpretation of Romanticism in the 1920s and his engagement with psychoanalysis in the 1930s. Throughout his writings, however, Mann's continuing preoccupation with Weimar Classicism enables us to reread the development of other aspects of his thought as an attempt in dark times to preserve and develop a tradition of humanism that is distinctively German as well as European. In 'On the German Republic' (1922), Mann defined his conservatism as standing 'not in the service of the past and of reaction, but in the service of the future' (ix, 829); as he termed it in 1926, it was a 'Zukunftskonservatismus' (conservatism of the future), 'serene, removed from all crude, sentimental atavism', and a conservatism 'which, its eye fixed on the new, plays with old cultural forms, in order to rescue them from oblivion' (ix, 189).