 This analysis of the role of imaginative creations of art can also help us to understand the role of philosophy within his own novels, particularly in Nausea, a novel which Sartre began as he was studying Husserl in Berlin. In this novel Sartre’s pre-phenomenological interest for the irreducibility of contingency intersects with his newly-acquired competences in phenomenological analyses, making Nausea a beautifully illustrated expression of the metaphysical register Sartre gave to Husserl’s conception of intentionality. The feeling of nausea that Roquentin, the main character of Sartre’s novel, famously experienced in a public garden while obsessively watching a chestnut tree, accounts for his sensitivity to the absolute lack of necessity of whatever exists. Sartre understands this radical absence of necessity as the expression of the fundamental contingency of being. Roquentin’s traumatic moment of realisation that there is absolutely no reason for the existence of all that exists illustrates the intuition that motivated Sartre’s philosophical thinking since the very beginning of his intellectual career as a student at the Ecole Normale Supérieure, as Simone de Beauvoir recalls (1981 [1986]). It constitutes the metaphysical background of his interpretation of intentionality, which he would come to develop and systematise in the early dense parts of Being and Nothingness. While the experience of nausea when confronting the contingency of the chestnut tree does not give us conceptual knowledge, it involves a form of non-conceptual ontological awareness that is of a fundamentally different order to, and cannot be derived from, our conceptual understanding and knowledge of brute existence.