this also is very old, much like witchcraft, and sometimes connected to it. ask the ancient greeks: > in one tale, demeter transformed herself into a mare to escape poseidon, but poseidon counter-transformed himself into a stallion to pursue her, and succeeded in the rape. caenis, having been raped by poseidon, demanded of him that she be changed to a man. he agreed, and she became caeneus, a form he never lost, except, in some versions, upon death.   shifting basically even in ancient greece they already knew that women turn to the beasts when they feel violated by man
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