HEIDEGGER'S ONTOLOGY IN BEING AND TIME

On page 67 of Being and Time Heidegger writes, “The ‘essence’ of Dasein lies in its existence.” This formula was the inspiration for Jean-Paul Sartre's better known thesis that “existence precedes essence.” What can it mean to say that our “essence” lies in our existence, and why does Heidegger put “essence” in quotation marks? We may assume that by the latter device Heidegger means to indicate that the sense in which Dasein has an essence is rather different from the sense in which non-human things have essences, or perhaps even that Dasein does not really have an essence at all. In the preceding paragraph he writes,

The phrase “to-be” is more gerundive than gerund; it expresses the idea that we have our being to be, as we may have tasks to do or miles to walk. Our essence, our “what-we-are” (or better, “who-we-are”), is determined by how we live, and how we live is structured by how we are called upon to live. Called upon by whom or what? By ourselves. (We shall explore this thought later.) In the paragraph in which Heidegger makes this statement he infers from it that Dasein is not an entity “present-at-hand.