The central point being made is the following: “Koans are not nonsensical. This is the point I want to stress. There is a standpoint from which they make sense and they’re perfectly logical. They do involve a lot of word play, punning, joking, metaphorical flights of fancy, but all of those are grounded in an understanding of the point being made.” He concludes this analysis saying that “The meaning of any koan can be explained in logical philosophical language, but that’s not the rules of the game. The rules of the rhetorical game of commenting on them call for a rhetorical response in kind.”
A monk asked Zhaozhou, “Even in a dog, is there Buddha nature or not?”
And Zhaozhou said “Wu” (or in Japanese “Mu”).
A monk asked Zhaozhou, “Like what was the intent of the ancestral founder coming from the west?”
Zhaozhou said, "The cypress tree in front of the hall.”