"La Nausée" allows Sartre to explain his philosophy in simplified terms. Roquentin is the classic existentialist hero whose attempts to pierce the veil of perception lead him to a strange combination of disgust and wonder. For the first part of the novel, Roquentin has flashes of Nausea that emanate from mundane objects. These flashes appear seemingly randomly, from staring at a crumpled piece of paper in the gutter to picking up a rock on the beach. The feeling he perceives is pure disgust: a contempt so refined that it almost shatters his mind each time it occurs. As the novel progresses, the Nausea appears more and more frequently, though he is still unsure of what it actually signifies. However, at the base of a chestnut tree in a park, he receives a piercingly clear vision of what the Nausea actually is. Existence itself, the property of existence to be something rather than nothing was what was slowly driving him mad. He no longer sees objects as having qualities such as color or shape. Instead, all words are separated from the thing itself, and he is confronted with pure being.