  In the novel Nausea (1936) Jean-Paul Sartre described a bizarre course of experience in which the protagonist, writing in the first person, describes how ordinary objects lose their meaning until he encounters pure being at the foot of a chestnut tree, and in that moment recovers his sense of his own freedom. In Being and Nothingness (1943, written partly while a prisoner of war), Sartre developed his conception of phenomenological ontology. Consciousness is a consciousness of objects, as Husserl had stressed. In Sartre’s model of intentionality, the central player in consciousness is a phenomenon, and the occurrence of a phenomenon just is a consciousness-of-an-object. The chestnut tree I see is, for Sartre, such a phenomenon in my consciousness. Indeed, all things in the world, as we normally experience them, are phenomena, beneath or behind which lies their “being-in-itself”. Consciousness, by contrast, has “being-for-itself”, since each consciousness is not only a consciousness-of-its-object but also a pre-reflective consciousness-of-itself (conscience de soi). Yet for Sartre, unlike Husserl, the “I” or self is nothing but a sequence of acts of consciousness, notably including radically free choices (like a Humean bundle of perceptions).