Chapter 22, Part 8 - Chuang Tzu

Bright Dazzlement asked Non-Existence, "Sir, do you exist or do you not exist?" Unable to obtain any answer, Bright Dazzlement stared intently at the other's face and form - all was vacuity and blankness. He stared all day but could see nothing, listened but could hear no sound, stretched out his hand but grasped nothing.

"Perfect!" exclaimed Bright Dazzlement. "Who can reach such perfection? I can conceive of the existence of nonexistence, but not of the nonexistence of nonexistence. Yet this man has reached the stage of the nonexistence of nonexistence. How could I ever reach such perfection!"
~ Burton Watson translation via Terebess Asia Online ~

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