here were two monks from India debating. One of them said, “The banner is flapping.” The other said, “The wind is flapping.” They went back and forth and could not settle the question. Then Huineng (6th Zen Patriarch) said, “It is not the banner that is flapping. It is not the wind that is flapping. It is your mind that is flapping.” 

Hui Neng (638-713), Huineng also commonly known as the Sixth Patriarch of Chan, is a central figure in the early history of Chinese Chan Buddhism. According to tradition he was an uneducated layman who suddenly attained awakening upon hearing the Diamond Sutra.