Analyzing the fundamental ontology of Dasein in Martin Heidegger's Being and Time, this essay details the essential relation ship between the mood of "anxiety" (Angst) and Dasein's authentic comportment to existence. Although a highly disturbing experience, anxiety holds the potential for enlightenment, as it opens Dasein to the fundamental characteristics of its temporal authenticity. Dasein assents to its Selfhood and enacts its freedom in a "resolute," authentic manner only when it grasps the difficult and burdensome aspects of life revealed by way of Angst's attunement. Thus, I argue that anxiety is the single most important mode of human attunement that Heidegger describes.