The Second Sex by Simone de Beauvoir (1949)

Open the book and the ground you stand on begins to move. What you were raised to call nature, the patience and the softness and the instinct for the home, Simone de Beauvoir shows to be something built, brick by brick, by every institution that ever needed woman to stay the second sex. Her famous sentence, "One is not born, but rather becomes, a woman," is no slogan; it is the hinge on which two thousand years of Western thought swings open. Borrowing the tools of existentialism, she asks the question no one had dared put first: not whether women deserve equality, but what "woman" even is, and who decided it. Her answer is merciless and exhilarating. She moves through ancient myth, Freud, the dream of marriage, the long labour of motherhood, and reveals the eternal feminine to be no eternal thing at all but a daily achievement, renewed by everyone around you and, quietly, by you. To read it is to feel a cage you never noticed soften into a choice.