One is not born, but rather becomes, a woman.

This, the opening line of Book II, is de Beauvoir’s most famous statement. It represents the logical continuation of the proofs de Beauvoir offers in Book I to support her argument that femininity does not arise from differences in biology, psychology, or intellect. Rather, femininity is a construction of civilization, a reflection not of “essential” differences in men and women but of differences in their situation. Situation determines character, not the other way around. Woman is not born fully formed; she is gradually shaped by her upbringing. Biology does not determine what makes a woman a woman—a woman learns her role from man and others in society. Woman is not born passive, secondary, and nonessential, but all the forces in the external world have conspired to make her so. Every individual self, regardless of gender, is entitled to subjectivity; it is only outside forces that have conspired to rob woman of this right. Destiny is not a cosmic force but a human choice, the result of culture and circumstance.