Paintings now in the Academy detailed fanaticism in flagellants and the Inquisition, the phenomenon of witchcraft, the plight of prisoners and fantasies of the madhouse that mocked the " normal" world.
This is confirmed by the growth in the popularity of folklore, witchcraft, tarot and crystals, which has been understood as a reaction to the decline of organised religion.
Well, if the answer isn't witchcraft, it just might be the sheer number of cultural, historical, and literary allusions packed into her wizarding universe.