A wandering monk passed by the courtyard of a monastery where he heard two groups of monks arguing about the temple flag fluttering in the breeze.
“It is the flag that moves,” one group argued.
“No, it is the wind that moves,” argued the other group.
Back and forth they argued, responding to the logic of the other side, coming up with new rationale for their respective positions. But it just came down to, “It is the wind that moves, it is the flag that moves.”
After listening for a while, the itinerant monk interrupted them and said, “If you look more closely you will see that it is neither the flag nor the wind that moves — what moves is your mind.”