The background story of this Koan
Hyakujo wished to send a monk to open a new monastery.
He told his pupils that whoever answered a question most ably would be appointed.
Placing a water vase on the ground, he asked:
"Who can say what this is without calling its name?"
The chief monk said: "No one can call it a wooden shoe."
Isan, the cooking monk, tipped over the vase with his foot and went out.
Hyakujo smiled and said: "The chief monk loses." And Isan became the master of the new monastery.
The original Chinese Goang
Venerable Guishan: When he was still first at Baizhang among the assembly and filling the Canon-Seat.
Baizhang was going to choose the host of Great Gui, therefore requested the Head-Seat be compared together with the lower crowd, and put forth words to investigate the person who might go there.
Baizhang proceeded to pick up the clean-water-bottle and place it on the floor, setting up a question saying, “You can not call this a clean-bottle. What do you call this?"
Therefore the Head-Seat said, “One also can not call this a tree stump!"
Baizhang still asked from Shan. Shan therefore leaped and tipped over the clean-bottle, then exited.
Baizhang laughed and said, "The First-Seat is defeated, and it’s still Brother Shan!"
This is the reason for the decree to govern the mountain.
Traditional Commentaries and .... Poems (Gata)
Isan was brave enough, but he could not escape Hyakujo's trick.
After all, he gave up a light job and took a heavy one.
Why, can't you see, he took off his comfortable hat and placed himself in iron stocks.
Guishan, one time bravely struggled to leave, but jumping from Baizhang’s protecting sty, he did not come forth.
When this is picked up and examined in the future, it will then be heavy, it will not then be light.
For what reason did he win liberation to transfer to his own head to raise and carry the iron cangue?