Found while rummaging at Social Fiction.
"I have made a simple flicker machine. You look at it with your eyes shut and the flicker plays over your eyelids. Visions start with a kaleidoscope of colors on a plane in front of the eyes and gradually become more complex and beautiful, breaking like surf on a shore until whole patterns of color are pounding to get in. After awhile the visions were permanently behind my eyelids and I was in the middle of the whole scene with limitless patterns being generated around me. There was an almost unbearable feeling of spatial movement for a while but It was well worth getting through for I found that when it stopped I was high above the earth in a universal blaze of glory. Afterwards I found that my perception of the world around me had increased very notably. All conceptions of being dragged or tired had dropped away..."- Brion Gysin [LINK]