Menstrual blood’s impurity derives from its link to feminine fertility, not the blood itself

Evidence

But it is especially striking that menstrual blood’s effects are linked to the ideas of cream going sour, mayonnaise that does not take, fermentation, and decomposition; it is also claimed that it is apt to cause fragile objects to break; to spring violin and harp strings; but above all it influences organic substances that are midway between matter and life; this is less because it is blood than because it emanates from genital organs; even without knowing its exact function, people understood it to be linked to the germination of life: ignorant of the existence of the ovary, the ancients saw in menstruation the complement of the sperm. In fact, it is not this blood that makes woman impure, but rather, this blood is a manifestation of her impurity; it appears when the woman can be fertile; when it disappears, she becomes sterile again; it pours forth from this womb where the fetus is made. The horror of feminine fertility that man experiences is expressed through it. — Simone de Beauvoir, The Second Sex, 338

Categorization

• DEFINE: Clarifies how premodern cultures conflated menstruation with fertility — the ancients saw it as the complement of sperm, lacking knowledge of the ovary.
• XREF: connects to: Menstrual blood was ambivalent in matriarchal societies—both destructive and beneficial.; Incest taboos and menstruation prohibitions both express man’s fear of feminine fertility — Simone de Beauvoir, The Second Sex, 339; Menstrual impurity was ritually treated identically to venereal disease impurity. — Simone de Beauvoir, The Second Sex, 333 (+1 more)

Broader Connections

• Incest taboos and menstruation prohibitions both express man’s fear of feminine fertility #expands (0.88) — Simone de Beauvoir, The Second Sex, 339