Ancestor Ma's Duck Flies Away (BCR53)

KOAN:

Once Ancestor Ma and Baizhang were taking a walk when a wild duck flew by.
“What’s that?” asked the Ancestor.
“A wild duck,” said Baizhang.
“Where did it go?”
“It flew away.“
The Ancestor twisted Baizhang’s nose, and Baizhang cried out in pain.
“When did it fly away?“ asked the Ancestor.

—Blue Cliff Record Case 53

(transl. by John Tarrant & Joan Sutherland)