He also knows incantations, the kind hunters employ when they go into the mountains. They are called mountain blackmagic or hexes and he has no qualms about using them. He really believes they can drive wild animals into pits or get them to step into snares. They aren’t used only on animals, they’re also used against other human beings for revenge. A victim of mountain blackmagic won’t be able to find his way out of the mountains. They are like the “demon walls” I heard about as a child: when a person has been traveling for some time at night in the mountains, a wall, a cliff or a deep river appears right in front of him, so that he can’t go any further. If the spell isn’t broken the person’s feet don’t move forward and even if he keeps walking, he stays exactly where he started off. Only at daybreak does he discover that he has been going around in circles.
Gao Xingjian (translated by Mabel Lee), Soul Mountain, 1990