Wow! Ride on the Edge?

An intriguing Koan to crack:

 

Ride your horse along the edge of a sword; hide yourself in the middle of flames.

 

What on earth does that mean?

WOW! - No Q: No A?

 A Koan:

A monk asked Master Yun-men: “What is the fundamental teaching in life?”

Yun-men: “No question, no answer.”

 

What does that mean?

WOW! Cloud in the Book

A Koan to crack:

 Cloud in the book!

 

Question: What does that mean?

 

WOW! What separates the Two

Here is another famous Zen Koan to crack:

"Knock - Knock"

Question: What separates the two?

Hint: If needed, strike a table with your knuckles to produce the 'knock-knock' effect.