This chapter discusses the use of enigma in Sein und Zeit and shows how and why the relations between Heidegger’s central conceptual pairings—state-of-mind and understanding, thrownness and projection, facticity and existentiality—are described by Heidegger as enigmatic. It seeks to read Heidegger’s analyses of each of these concepts against the grain in order to bring into view much more resilient notions of facticity and thrownness that place in doubt the move to existentiality, projection, and authenticity. There are two phrases that provide a clue to what is going on in Sein und Zeit: Dasein ist geworfener Entwurf and Dasein existiert faktisch. The chapter provides a reinterpretation of Heidegger’s Sein und Zeit through an internal commentary on the text in its own terms rather than through some sort of external, strategic and potentially reductive reading.