Hui Neng was an illiterate peasant who had experienced a sudden awakening upon hearing the Lotus Sutra recited aloud, and went to join the monastery of the Fifth Patriarch of Zen. The Patriarch recognized that Hui Neng was in the process of awakening, but rather than openly acknowledge this he assigned him to care for the pigs on the outskirts of the monastery to protect him from the academic and spiritual corruptions of the other monks.
However, one day as Hui Neng was going about his work he heard two monks nearby engaging in a classic argument about spiritual reality. They were watching the large monastery flag waving in the wind, and one monk was arguing that it was the flag that was moving, while the other argued that it was the wind that was moving. These two arguments correspond to classic spiritual viewpoints about the nature of reality, and while listening to the learned monks argue, Hui Neng could not hold back. He interrupted them and told them, “It is neither the flag that moves, nor the wind that moves. It is your mind that moves”.
The two monks were silenced, and Hui Neng went about his work tending to the pigs.