Zhuangzi dreamed he was a butterfly

The butterfly dream

Another well-known part of the book, which is also found in Chapter 2, is usually called "Zhuangzi dreamed he was a butterfly" (莊周夢蝶 Zhuāng Zhōu mèng dié).

Once Chuang Chou dreamt he was a butterfly, a butterfly flitting and fluttering around, happy with himself and doing as he pleased. He didn't know he was Chuang Chou. Suddenly he woke up and there he was, solid and unmistakable Chuang Chou. But he didn't know if he was Chuang Chou who had dreamt he was a butterfly, or a butterfly dreaming he was Chuang Chou. Between Chuang Chou and a butterfly there must be some distinction! This is called the Transformation of Things. (2, tr. Burton Watson 1968:49)

This hints at many questions in the philosophy of mind, philosophy of language, and epistemology. The name of the passage has become a common Chinese idiom, and has spread into Western languages as well. It appears, inter alia, as an illustration in Jorge Luis Borges' famous essay "A New Refutation of Time", and may have inspired Howard Phillips Lovecraft's 1918 short story "Polaris".