… no matter how otherwise heteroclite, they [theoretical innovations of western marxists] share one fundamental embleme: a common and latent pessimism. All the major departures or developments of substance within this tradition are distinguished from the classical heritage of historical materialism by the darkness of their implications or conclusions. In this respect, between 1920 and 1960, Marxism slowly changed colours in the West. The confidence and optimism of the founders of historical materialism, and of the successors, progressively disappeared. Virtually every one of the significant new themes in the intellectual muster of this epoch reveals the same diminution of hope and loss of certaintly.