In "Being and Nothingness: An Essay on Phenomenological Ontology" (1943), Jean-Paul Sartre (1905–1980) applied the dialectic of intersubjectivity to describe how the world is altered by the appearance of the Other, of how the world then appears to be oriented to the Other person, and not to the Self. The Other appears as a psychological phenomenon in the course of a person's life, and not as a radical threat to the existence of the Self. In that mode, in "The Second Sex" (1949), Simone de Beauvoir (1908–1986) applied the concept of Otherness to Hegel's dialectic of the "Lord and Bondsman" ("Herrschaft und Knechtschaft", 1807) and found it to be like the dialectic of the Man–Woman relationship, thus a true explanation for society's treatment and mistreatment of women.