Simone de Beauvoir (1908–1986) was a French existentialist philosopher, writer, feminist, and political activist whose work profoundly shaped twentieth-century thought and the modern feminist movement. Educated at the Sorbonne, where she met Jean-Paul Sartre, she became one of the first women to pass the agrégation in philosophy. Her groundbreaking work The Second Sex (1949) is widely considered the founding text of modern feminism. In it she analyzed the mechanisms by which women have been constructed as "the Other" and argued that "one is not born, but rather becomes, a woman." Drawing on existentialism, Marxism, and psychoanalysis, she demonstrated that femininity is not a natural condition but a social construction. Beyond feminist philosophy, she wrote acclaimed novels (The Mandarins won the Prix Goncourt), memoirs that provide an invaluable portrait of twentieth-century intellectual life in Paris, and philosophical essays on ethics and aging. She was politically active throughout her life, supporting Algerian independence and championing reproductive rights.