This text re-issues an important work by Lucien Goldmann, based on his university lectures from 1967-8, and first published in English in 1977. It focusses upon two of the twentieth century's most important philosophers, György Lukács and Martin Heidegger, demonstrating the origins of of existenialist thought in the implicit connection between the two. This book represents the application of methodology already developped in The Hidden God and also sees Goldmann elaborating the differences between himself and Lukács for the sake of defining his own Marxist perspective.