 Sartre’s existentialism drew its immediate inspiration from the work of the German philosopher, Martin Heidegger. Heidegger’s 1927 Being and Time, an inquiry into the “being that we ourselves are” (which he termed “Dasein,” a German word for existence), introduced most of the motifs that would characterize later existentialist thinking: the tension between the individual and the “public”; an emphasis on the worldly or “situated” character of human thought and reason; a fascination with liminal experiences of anxiety, death, the “nothing” and nihilism; the rejection of science (and above all, causal explanation) as an adequate framework for understanding human being; and the introduction of “authenticity” as the norm of self-identity, tied to the project of self-definition through freedom, choice, and commitment. Though in 1946 Heidegger would repudiate the retrospective labelling of his earlier work as existentialism, it is in that work that the relevant concept of existence finds its first systematic philosophical  formulation.[3]