I'm not familiar with the book, but I am familiar with "Gutei's Finger", as well as some of the other koans. I have to admit it surprised me a little to come across a reference to Ch'an here, but in another sense, it's no surprise at all.
"A monk asked, 'What is the fact of my nature?' The master replied, 'Shake the tree, and the birds take to the air; startle the fish, and the water becomes muddy.'"
Give sorrow words: the grief that does not speak
Whispers the o'er-fraught heart and bids it break.
-William Shakespeare, Macbeth, Act IV, Sc. III