Simone de Beauvoir's feminist ideas were significantly shaped by her personal experiences, particularly her relationships and education. Growing up in a patriarchal society, she became acutely aware of women's societal roles. Her partnership with philosopher Jean-Paul Sartre further influenced her thoughts on existentialism and gender inequality, as they often discussed the limitations placed on women. Additionally, her struggles with sexuality and identity motivated her to critique the societal expectations that constrained women's freedom and autonomy. These experiences formed the basis for her seminal work, "The Second Sex," where she famously declared that "one is not born, but rather becomes, a woman."