Black Magic is Not a Myth in Articles by Aleister Crowley.

“The apparatus has lost its guiding control, the spiritual side of a man, and it can be—and often is—taken by elemental spirits of evil and turned to any base use.” [via, also]

Consider also:

  1. “Through their mediumistic acts, spiritists sometimes get hold of disintegrated pieces of the mental apparatus of a man or woman who has died recently.”
  2. “Intellectual Beauty has not only the happy dead to do her will, but ministering spirits who correspond to the Devas of the East, and the Elemental Spirits of mediaeval Europe, and the Sidhe of ancient Ireland”
  3. “This is supposed to release the powers of evil and bring them into alliance. (It is rather the case of the mouse trying to make a friend of the cat!)”
  4. “In Paris, and even in London, there are misguided people who are abusing their priceless spiritual gifts to obtain petty and temporary advantages through these practices.”
  5. “Later, when I was transferring my apparatus to my house in Scotland, I employed two workmen to remove the mirrors. As they were working they were suddenly overcome, knocked out by unseen assailants. It took several hours to revive them. People passing the doorway suddenly fell down in fits. That flat remained without a tenant for years after I had left it. All this was because I had not enough experience to control the forces.”