In "Free and Easy Wandering," Zhuangzi uses the story of the Kun transforming into the Peng to express the highest state of freedom.
In the northern darkness there was a fish, called Kun. The Kun was so vast that no one knew how many li across it was. It transformed into a bird, called Peng. The Peng's back was so wide that no one knew how many li across it was. When it roused itself and flew, its wings were like clouds hanging from the sky.
Through this extravagant imagination, Zhuangzi tells us a profound truth: true freedom is not the ability to go anywhere, but a mind no longer bound by external things.
The cicada and the little dove laughed at it: "When we decide to fly, we dart to the elm or the sandalwood, and when we don't reach them, we simply drop to the ground. Why would anyone go up ninety thousand li and head south?"
The cicada and dove cannot comprehend the Peng's realm. This is "small understanding cannot fathom great understanding" — those with narrow perspectives cannot grasp those with broader ones.
The morning mushroom knows nothing of the new and full moon. The summer cicada knows nothing of spring and autumn. Likewise, those trapped in daily trivialities cannot understand those who pursue freedom.
Zhuangzi's message: don't be the cicada or dove laughing at the Peng. The size of your world depends on the size of your heart. True freedom is not out there somewhere — it's in a mind free of attachment.