Georg Lukacs was dubbed "the philosopher of the October Revolution" and his masterpiece History and Class Consciousness (1923) is commonly held to be the foundational text for the tradition known as "Western Marxism" which includes the work of Theodor Adorno, Walter Benjamin, Ernst Bloch, Max Horkheimer, and Herbert Marcuse. However, as the liberating energies of the Russian Revolution were sapped by Stalinism, Lukacs was subjected to ferocious attack for "deviations" from the "party line". In the mid-1920s, Lukacs wrote a sustained and passionate response to this onslaught. Unpublished at the time, Lukacs himself thought the text had been destroyed. However, a group of researchers recently found the manuscript gathering dust in the newly opened archives of the CPSU in Moscow. Now, for the first time, this fascinating, polemical and intense text is available in English. It is a crucial part of a hidden intellectual history and will transform interpretations of Lukacs's oeuvre.