From
《庄子·逍遥游》 opening (Zhuangzi, 'Free and Easy Wandering,' Warring States, c. 300 BCE):
北冥有鱼,
其名为鲲。
鲲之大,
不知其几千里也 (In the Northern Ocean there is a fish called Kun. Kun is so vast that nobody knows how many thousand li it measures). The fish then transforms into the Peng bird and soars south - the founding image of Daoist cosmic perspective.