It starts with an ordinary white candle. Stare into the flame and you’ll notice three distinct parts: the yellow outside, the mauve interior, and the tiny black area right in the middle. Focus your attention there, and soon enough, your mind will go completely blank.

This was how Henry Sugar learned to see with his eyes closed. It was the beginning of a new and rewarding life; a wonderful story, if you will. 

“‘John,’ [Henry] said, addressing the butler, ‘can you find me a candle? Just an ordinary white candle.’”
- Roald Dahl, The Wonderful Story of Henry Sugar