Zhuangzi on dreaming butterfly

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.
— Zhuangzi (romanized Hanyu Pinyin transliteration; sometimes spelled Chuang Chou, Chuang Tsu, Chuang Tzu, Zhuang Tze, Chouang-Dsi, Chuang Tse, Chuangtze, Master Chuang) in The Complete Works of Chuang Tzu, translated by Burton Watson, (New York: Columbia University Press, 1968), p. 49.

"Once Chuang Chou dreamt he was a butterfly"

This is an often-mentioned idea and text, and it has been adapted in many ways. Some of the examples I have observed include:

Once I dreamed I was a butterfly, and now I no longer know whether I am Chuang-tzu, who dreamed I was a butterfly, or whether I am a butterfly dreaming that I am Chuang-tzu.