Surely, in a way, woman is mysterious, “mysterious like everyone,” according to Maeterlinck. Each one is subject only for himself; each one can grasp only his own self in his immanence; from this point of view, the other is always mystery. In men’s view, the opacity of the for-itself is more flagrant in the feminine other; they are unable to penetrate her unique experience by any effect of sympathy; they are condemned to ignorance about the quality of woman’s sexual pleasure, the discomforts of menstruation, and the pains of childbirth. The truth is that mystery is reciprocal: as another, and as a masculine other, there is also a presence closed on itself and impenetrable to woman in the heart of every man; she is without knowledge of male eroticism. But according to a universal rule already mentioned, the categories in which men think are constituted from their point of view as absolutes: they fail to understand reciprocity here as everywhere. As she is mystery for man, woman is regarded as mystery in herself.
Simone de Beauvoir, The Second Sex, translated by Constance Borde and Sheila Malovany-Chevallier