"Men have scars, women mysteries": Blood magic in ASOIAF as a reproduction of Aristotle's blood hierarchy

In the fourth century BCE, Aristotle wrote about blood hierarchies. He believed that all bodily fluids were the same, just more or less purified versions of blood. He named semen as the top of this hierarchy, calling it "the final form of nourishment," the pinnacle of purification. Of course, he placed menstrual blood at the bottom of the hierarchy:

Now the weaker creature [woman] too must of necessity produce a residue greater in amount and less thoroughly concocted, and this, if such is its character, be of necessity a volume of bloodlike fluid... the secretion in females which answers to semen is the menstrual fluid.

This idea that men's bodily secretions were somehow cleaner and more refined than women's (shockingly) prevailed in Europe throughout the Middle Ages. This resulted in a lot of, let's just say, interesting tall tales—my personal favorite being the myth that women with irregular or no periods could shoot acidic menstrual blood out of their eyes like lasers.

I dunno, watching election news kinda makes me think that myth didn't go away.

Interestingly, in George Martin's A Song of Ice and Fire series, women's menstrual blood isn't construed as acidic or bile-like, or really even (all that) disgusting. It's another form of blood, and the only time men concern themselves with female blood at all seems to be when they're concerned with whether a girl is old enough to marry, and as proof of her virginity on her wedding night.

But George doesn't get off the hook that easily. See, in his world, women's blood may not create deep trenches in the earth or poison babies, but it is the only blood explicitly used in magic and prophecy. And, in a series comprised of 5 books and roughly 1,770,000 words (so far), that connection isn't to be ignored.

Blood magic starts off in the first book of the series, A Game of Thrones, when the maegi Mirri Maaz Duur uses both horse's blood to force a miscarriage onto Daenerys—a bloody affair in and of itself—to keep Khal Drogo alive, in a vegetative state. The magic Dany had begged the witch to do involved her own blood and her child's to do, and it gave her only a husk of her husband. 

The next interaction with blood magic isn't much better: A Feast for Crows opens with a young Cersei going to Maggy the Frog (also a maegi—white people just can't pronounce foreign words) for her fortune. The witch requires Cersei's blood to tell her, and the future she reads is dark, haunting Cersei to the present day.

Even in sheer prophecy, not even blood magic, women's blood is key. In the third book, A Storm of Swords, Patchface (the court fool of Stannis Baratheon) sings a lunatic song that later turns out to prophesy the Red Wedding, one of the biggest turning points of the series' main military conflict, the War of the Five Kings. He sings:

Fool's blood
King's blood
Blood on the maiden's thigh
But chains for the guests
And chains for the bridegroom
Aye, aye, aye 

Thus, the Red Wedding, at which the war loses its best contender at his uncle's wedding, it is still of some fundamental importance to mention that a woman, and a maiden nonetheless, will bleed. Even in the magic of prophecy, far removed from blood magic, blood is vital, and the blood of women is essential.

So George doesn't write about women's blood being disgusting, or lesser, in any such terms, but he instead writes another iteration of the same perspective: women's blood is the only blood imbued with magic, and women's blood should be feared for it. There is as much a blood hierarchy in ASOIAF as there is in medieval literature and thought—when men are wounded in battle, it's honorable, but when women bleed, it's often sorcery.

In A Clash of Kings, Cersei Lannister tells Sansa Stark, "A woman's life is nine parts mess to one part magic, you'll learn that soon enough... and the parts that look like magic turn out to be the messiest of all." Little does Sansa—or most readers—know just how right she is.