Once Zhuang Zhou dreamt he was a butterfly, a butterfly flitting and fluttering about, happy with himself and doing as he pleased. He did not know that he was Zhuang Zhou. Suddenly he woke up, and there he was, solid and unmistakable Zhuang Zhou. But he did not know if he was Zhuang Zhou who had dreamt he was a butterfly, or a butterfly dreaming that he was Zhuang Zhou.
Cook Ding was cutting up an ox for Lord Wenhui. His knife glided through as though there were nothing there. Nineteen years I have used this knife, and it is still as good as when it first came from the grindstone. There are spaces between the joints, and the blade of the knife has no thickness. If you insert what has no thickness into such spaces, there is plenty of room for the blade to move about.