騰虹遊於霧露，乘於風雨而行，非千里不止，然則暮託宿於鰌鱣之穴。
When flying birds assume formations, hawks and vultures do not strike them.
When common people gather into multitudes, sages let them live in peace.
所以然者何也？
Writhing serpents wander through the mists and dew, riding on the wind, but, when evening comes, they lodge in caves of pikes and eels.
用心不一也。
How does this come about?
It is because their aims lack fixity.
夫蚯蚓內無筋骨之強，外無爪牙之利，然下飲黃泉，上墾晞土，所以然者何也？
Earthworms are devoid of the strength that inheres in bony joints and are without the cutting ability of claws and teeth, yet they drink from the Yellow Springs below and break up the arid earth unassisted.
用心一也。
How does this come about?
It is because their aims are fixed.