I Make Myself Invisible in Articles by Aleister Crowley.
“According to the rules of magic, I built a terrace with a northern aspect and carted river sand to it.
I worked in the breakfast-room at making the talismans which were necessary to my purpose. The sun was streaming into the room, but in vain; there was a darkness which could be felt. The demons, evil forces, had congregated round me so thickly that they were shutting off the light. It was a comforting situation. There could be no more doubt of the efficiency of the operation.” [via, also]