Simone de Beauvoir Publishes The Second Sex

In 1949, French existentialist philosopher Simone de Beauvoir published Le Deuxième Sexe (The Second Sex), a groundbreaking analysis of women's oppression throughout history. Her central argument — "One is not born, but rather becomes, a woman" — distinguished biological sex from socially constructed gender, a distinction that became foundational to feminist theory. Beauvoir applied existentialist philosophy to show how women had been defined as the "Other" relative to men, denied authentic selfhood and freedom. The book was initially controversial (the Vatican placed it on the Index of Forbidden Books) but became the intellectual cornerstone of second-wave feminism and gender studies.