Simone Lucie Ernestine Marie Bertrand de Beauvoir (; French: [sim?n d? bovwa?] (listen); 9 January 1908 – 14 April 1986) was a French writer, intellectual, existentialist philosopher, political activist, feminist and social theorist. Though she did not consider herself a philosopher, she had a significant influence on both feminist existentialism and feminist theory.De Beauvoir wrote novels, essays, biographies, autobiography and monographs on philosophy, politics, and social issues. She was known for her 1949 treatise The Second Sex, a detailed analysis of womens oppression and a foundational tract of contemporary feminism; and for her novels, including She Came to Stay and The Mandarins. She was also known for her lifelong relationship with French philosopher Jean-Paul Sartre.