Eno's Flag

六祖、因風颺刹幡。有二僧、對論。 一云、幡動。一云、風動。 往復曾未契理。 祖云、不是風動、不是幡動、仁者心動。 二僧悚然。

The wind was flapping a temple flag, and two monks started an argument. One said the flag moved, the other said the wind moved; they argued back and forth but could not reach a conclusion. The Sixth Patriarch said, “It is not the wind that moves, it is not the flag that moves; it is your mind that moves.” The two monks were awe-struck.

The Gateless Gate, Case 29