“I am going to pose a question,” King Milinda said to the Venerable Nagasena.
“Can you answer?”
Nagasena said, “Please ask your question.”
The king said, “I have already asked.”
Nagasena said, “I have already answered.”
The king said, ‘What did you answer?”
Nagasena said, “What did you ask?”
The king said, “I asked nothing.”
Nagasena said, “I answered nothing.”

– Zen Mondo