“The best blood is of the moon, monthly: then the fresh blood of a child, or dropping from the host of heaven: then of enemies; then of the priest or of the worshippers: last of some beast, no matter what.” —AL III:16
As most Thelemites know, menstrual blood is an important part of a number of magical practices, possibly including Cakes of Light (and if so it’s burnt to black ash before being added to CoL dough, nonetheless retaining its magical essence). This ingredient isn’t exclusive to Thelema, however. Hoodoo often includes the practice of sneaking menstrual blood into food or beverages for reasons like ensuring a man’s fidelity, controlling someone, or casting a love spell.
Rebel Circus tells us: There are few bodily fluids in the world more taboo and controversy-inspiring than menstrual blood. People react to periods the way you’d expect people to react to things that are way more unnatural and horrifying, especially considering that half the population has to deal with their menstrual cycle at some point in their lives. That’s why people react so strongly when we hear stories about people that involve the stuff: periods are taboo and nobody wants to talk about them. A great example of this taboo in action is the backlash an unknown woman received on the Internet for revealing that she uses her menstrual blood to cook for her husband.
Thanks to Fr. Von Hohenheim for the tip!