Hogen, a Chinese Zen teacher, lived alone in a small temple in the country. One day four traveling monks appeared and asked if they might make a fire in his yard to warm themselves.
While they were building the fire, Hogen heard them arguing about subjectivity and objectivity.
He joined them and said: "There is a big stone. Do you consider it to be inside or outside your mind?"
One of the monks replied: "From the Buddhist viewpoint everything is an objectification of mind, so I would say that the stone is inside my mind."
"Your head must feel very heavy," observed Hogen, "if you are carrying around a stone like that in your mind."