Zhuangzi, Chapter on Free and Easy Wandering
Legend has it that in the Northern Sea there was a huge fish named Kun, which was so immense that it could transform into a giant bird named Peng. The Peng's back was vast, and its wings were like clouds hanging from the sky.
When the sea wind blew, the great Peng spread its wings and rode the wind, soaring straight up to a height of ninety thousand li, flying far away to the Southern Sea. The cicada and the little dove laughed at it for flying so far, but how could they understand the Peng's ambitions and vision?
Later, people used 'peng cheng wan li' to wish others a bright future, just like the great Peng bird that could fly thousands of miles and achieve extraordinary things.
