As the legend goes, during ancient times, in the expansive open country of North China, there was a kind of birds called "rocs".
The roc was very huge, with its back like a big mountain, and its wings like a stretch of cloud which could cover the sky. When it spread its wings, it could break through a storm and soar at a height of 90,000 li （1/2 kilometre） in the sky towards the sea in the south.
A small bird called the quail bounced on the ground, free and happy. It looked up at the roc soaring in the sky and couldn't help laughing:
"Hey, see how cocky you are！ Look at me, one jump can take me over 10 chi. How delightful！ Every day I come and go amid these weeds and thickets and fly freely. Don't I fly quite well too? But, where can you fly to anyway?"