One day about sunset, Zhuangzi dozed off and dreamed that he turned into a butterfly.

He flapped his wings and sure enough he was a butterfly...

What a joyfull feeling as he fluttered about, he completely forgot that he was Zhuangzi.

Soon though, he realized that that proud butterfly was really Zhuangzi who dreamed he was a butterfly, or was it a butterfly who dreamed he was Zhuangzi!

Maybe Zhuangzi was the butterfly, and maybe the butterfly was Zhungzi? This is what is menat by the "transformation of things."