Chuang Tzu and a disciple were crossing a foot bridge. Chuang Tzu notice the fish swimming past below and commented: "Being in their natural element and behaving as is natural for them, unencumbered by conflict, the fish feel truly happy." The disciple challenged Chuang Tzu: "How do you know how fish feel? You are not a fish!" To which Master Chuang replied: "You are not me. How do you know I don't know how fish feel?"