Chapter 22, Part 7C - Chuang Tzu

Grand Purity, having received these various answers, went and questioned No-Beginning, saying, "If this is how it is, then between No-End's declaration that he doesn't understand, and No-Action's declaration that he does, which is right and which is wrong?"

No-Beginning said, "Not to understand is profound; to understand is shallow. Not to understand is to be on the inside; to understand is to be on the outside."

Thereupon Grand Purity gazed up and sighed, saying, "Not to understand is to understand? To understand is not to understand? Who understands the understanding that does not understand?"

No-Beginning said, "The Way cannot be heard; heard, it is not the Way. The Way cannot be seen; seen, it is not the Way. The Way cannot be described; described, it is not the Way. That which gives form to the formed is itself formless - can you understand that? There is no name that fits the Way."

No-Beginning continued, "He who, when asked about the Way, gives an answer does not understand the Way; and he who asked about the Way has not really heard the Way explained. The Way is not to be asked about, and even if it is asked about, there can be no answer. To ask about what cannot be asked about is to ask for the sky.

"To answer what cannot be answered is to try to split hairs. If the hair-splitter waits for the sky-asker, then neither will ever perceive the time and space that surround them on the outside, or understand the Great Beginning that is within. Such men can never trek across the K'un-lun, can never wander in the Great Void!"
~ Burton Watson translation via Terebess Asia Online ~

Go here to read the introductory post to the chapters of the Book of Chuang Tzu.