Simone de Beauvoir (1908-86) was a French philosopher, novelist, and essayist, and the lifelong companion of Jean-Paul Sartre. De Beauvoir's first book, L'Invitee, was published in 1943. In 1945 she published Le Sang des autres, a novel dealing with the question of political involvement. Beauvoir's breakthrough work was the semiautobiographical Les Mandarins (1954), which won the Prix Concourt. Roman Catholic authorities banned it and de Beauvoir's feminist classic The Second Sex (1949), in which de Beauvoir argued that one is not born a woman; one becomes one .