Zhuangzi and The Happy Fish
子非鱼，焉知鱼之乐。 - 庄子
One day Zhuangzi and Huizi are strolling on Bridge Hao.
Zhuangzi: "Look how happy the fish are just swimming around in the river."
Huizi: "How do you know they are happy? You are not a fish."
Zhuangzi: "And you are not me. How do you know I don't know the fish are happy?"
Huizi: "Of course I'm not you, and I don't know what you think; But I do know that you're not a fish, and so you couldn't possibly know the fish are happy."
Zhuangzi: "Look, when you asked me how I knew the fish were happy, you already knew that I knew the fish were happy. I knew it from my feelings standing on this bridge."