Blood, Bread & Roses, How Menstruation created the world - Judy Grahn.

Menstrual blood is the only source of blood that is not traumatically induced. Yet in modern society, this is the most hidden blood, the one so rarely spoken of and almost never seen, except privately by women, who shut themselves in a little room to quickly and in many cases disgustedly change their pads and tampons, wrapping the bloodied cotton so it won’t be seen by others, wrinkling their faces at the odor, flushing or hiding the evidence away. Blood is everywhere, and yet the one, the only, the single name it has not publicly had, for many centuries, is menstrual blood.