 As Sartre and Merleau-Ponty would later do, Heidegger pursued these issues with the somewhat unlikely resources of Edmund Husserl’s phenomenological method. And while not all existential philosophers were influenced by phenomenology (for instance Jaspers and Marcel), the philosophical legacy of existentialism is largely tied to the form it took as an existential version of phenomenology. Husserl’s efforts in the first decades of the twentieth century had been directed toward establishing a descriptive science of consciousness, by which he understood not the object of the natural science of psychology but the “transcendental” field of intentionality, i.e., that whereby our experience is meaningful, an experience of something as something. The existentialists welcomed Husserl’s doctrine of intentionality as a refutation of the Cartesian view according to which consciousness relates immediately only to its own representations, ideas, sensations. According to Husserl, consciousness is our direct openness to the world, one that is governed categorially (normatively) rather than causally; that is, intentionality is not a property of the individual mind but the categorial framework in which mind and world become  intelligible.[4]