If her functioning as a female is not enough to define woman, if we decline also to explain her through ‘the eternal feminine’, and if nevertheless we admit, provisionally, that women do exist, then we must face the question: what is a woman?
To state the question is, to me, to suggest, at once, a preliminary answer. The fact that I ask it is in itself significant. A man would never get the notion of writing a book on the peculiar situation of the human male. But if I wish to define myself, I must first of all say: “I am a woman”; on this truth must be based all further discussion. A man never begins by presenting himself as an individual of a certain sex; it goes without saying that he is a man. The terms masculine and feminine are used symmetrically only as a matter of form, as on legal papers. In actuality the relation of the two sexes is not quite like that of two electrical poles, for man represents both the positive and the neutral, as is indicated by the common use of man to designate human beings in general; whereas woman represents only the negative, defined by limiting criteria, without reciprocity. In the midst of an abstract discussion it is vexing to hear a man say: “You think thus and so because you are a woman”; but I know that my only defense is to reply: “I think thus and so because it is true”, thereby removing my subjective self from the argument. It would be out of the question to reply: “And you think the contrary because you are a man”, for it is understood that the fact of being a man is no peculiarity. A man is in the right in being a man; it is the woman who is in the wrong. It amounts to this: just as for the ancients there was an absolute vertical with reference to which the oblique was defined, so there is an absolute human type, the masculine. Woman has ovaries, a uterus; these peculiarities imprison her in her subjectivity, circumscribe her within the limits of her own nature. It is often said that she thinks with her glands. Man superbly ignores the fact that his anatomy also includes glands, such as the testicles, and that they secrete hormones. He thinks of his body as a direct and normal connection with the world, which he believes he apprehends objectively, whereas he regards the body of woman as a hindrance, a prison, weighed down by everything peculiar to it. “The female is a female by virtue of a certain lack of qualities,” said Aristotle; “we should regard the female nature as afflicted with a natural defectiveness.” And St. Thomas for his part pronounced woman to be an “imperfect man”, an “incidental” being. This is symbolized in Genesis where Eve is depicted as made from what Bossuet called “a supernumerary bone” of Adam.
Thus humanity is male and man defines woman not in herself but as relative to him; she is not regarded as an autonomous being. Michelet writes: “Woman, the relative being….” And Benda is most positive in his Rapport d’Uriel: ‘The body of man makes sense in itself quite apart from that of woman, whereas the latter seems wanting in significance by itself. … Man can think of himself without woman. She cannot think of herself without man.” And she is simply what man decrees; thus she is called “the sex”, by which is meant that she appears essentially to the male as a sexual being. For him she is sex ― absolute sex, no less. She is defined and differentiated with reference to man and not he with reference to her; she is the incidental, the inessential as opposed to the essential. He is the Subject, he is the Absolute ― she is the Other.
Simone de Beauvoir, The Second Sex, 1949, trans. H. M. Parshley
(ellipses and emphasis original)