Originally posted by cycle:
Hogen, a chinese Zen teacher lived alone in a small temple in the city. One day four travelling monks appeared and asked if they might make a fire to warm themselves.
While they were building the fire, Hogen heard them arguing about subjectivity and obectivity. 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 the 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 such a stone like that in your mind."
~ Zen teacher Muju, Shaseki shu
Both subject (i.e mind) and object are void

One who sees object in subject, and then subject in object, knows non-duality.