I borrow the following text from Mahabharata – or one of its interpretations in the Internet.

“Never let Arjuna eat in the dark,” Drona told the palace cook.

Yet one night, as Arjuna was having supper, the wind blew out the lamp in Arjuna’s tent. Arjuna found himself eating, his hand going to his mouth with habitual skill. Arjuna realized that if his hand could find his mouth in the dark, it should be able to control an arrow even when he couldn’t see it.