Zhuangzi by Zhuang Zhou (-300)

Two philosophers stand on a bridge over the Hao river, watching minnows dart in the current. Look how happy the fish are, says one. You are not a fish, the other answers, so how can you know what fish enjoy, and back comes the reply: you are not me, so how do you know that I don't? The _Zhuangzi_ thinks this way throughout, by joke, parable, and sudden reversal, each turned to loosen your grip on a certainty that felt, a sentence earlier, like solid ground. Zhuang Zhou wrote in the chaos of the Warring States, and against that chaos he set not a system but a laugh. A man dreams he is a butterfly and wakes unsure which of them is dreaming the other. Few books hold their deepest thought so lightly, or trust delight to carry what argument cannot. Two thousand years on, the joke has not worn out.