The demonic is one of the major leitmotifs in Thomas Mann's Der Zauberberg. Like no other leitmotif, it unites in one image two major themes of Mann's text: the fascination with death and the deep-seated cultural opposition between East and West. In this manner Mann's novel aligns the crisis of West European civilization with an external demonic influence coming from the East. Mann's construction of the demonic in his novel can be traced, on the one hand, to his reflection on contemporary East/West issues. On the other hand, Mann's perception of demonism derives from his enthusiastic reception and subsequent rejection of Feodor Dostoevsky's political and philosophical views, particularly as expressed in his novel Demons (1872). I argue that, despite distancing himself from Dostoevsky amid his political conversion from conservatism to liberalism, Mann still borrows one of Dostoevsky's most controversial ideas—association of the loss of national identity with a devil's pact.