Marcuse's first published essay, "Contributions to a Phenomenology of Historical Materialism',¹ proposes a synthesis between Marxism and Heidegger's phenomenological existentialism. His goal is to produce a "concrete philosophy' capable of dealing with the central problems of the day. This remarkable philosophical debut anticipates later attempts to create a "phenomenological' or "existential' Marxism, and historically situates Marcuse within a current of "critical Marxism' that sought to reconstruct Marxism in order to provide an alternative to the "revisionism' of the dominant trends of the Second International and the dogmatism of Soviet Marxism.² The essay articulates an activist, practice-oriented interpretation of Marxism that has continued to shape Marcuse's later writings, and contains one of the first and best interpretations and critiques of Heidegger's influential Being and Time.