The philosophical and political development that converted Georg Lukács from a distinguished representative of Central European aesthetic vitalism into a major Marxist theorist and Communist militant has long remained an enigma. In this absorbing scholarly study, Michael Löwy for the first time traces and explains the extraordinary mutation that occurred in Lukács's thought between 1909 and 1929. Utilizing many as yet unpublished sources, Löwy meticulously reconstructs the complex itinerary of Lukács's thinking as he gradually moved towards his decisive encounter with Bolshevism. The religious convictions of the early Lukács, the peculiar spell exercised on him and on Max Weber by Dostoyevskyan images of pre-revolutionary Russia, the nature of his friendships with Ernst Bloch and Thomas Mann, are amongst the discoveries of the book. Then, in a fascinating case-study in the sociology of ideas, Löwy shows how the same philosophical problematic of Lebensphilosophie dominated the intelligentsias of both Germany and Hungary in the pre-war period, yet how the different configurations of social forces in each country bent its political destiny into opposite directions. The famous works produced by Lukács during and after the Hungarian Commune—Tactics and Ethics, History and Class Consciousness and Lenin—are analysed and assessed. A concluding chapter discusses Lukács's eventual ambiguous settlement with Stalinism in the thirties, and its coda of renewed radicalism in the final years of his life.