When the Sixth Patriarch saw a temple banner fluttering in the wind, two monks were arguing about it. One said, “The banner is moving”; the other said, “The wind is moving.” They went back and forth without ever reaching the principle.

The Patriarch said, “It is not the wind that moves, nor is it the banner that moves; benevolent sirs, your minds are moving.” The two monks were startled.

[Wumen said]

It is not the wind that moves, nor the banner that moves, nor the mind that moves. Where do you see the Patriarch? If you see this intimately here, then you will know that the two monks bought iron but obtained gold. The Patriarch could not suppress his laughter: what a complete disclosure!

[Verse]

Wind, banner, and mind move—one charge covers them all. They know only how to open their mouths, unaware that their words have already fallen.