The meaning of this sentence is: if you are not a king, why are you still exposed! It's dark, it's dark, why don't you go home? If it's not for the monarch, why are you still in the mud!
Extended data:
National Wind, Strong Wind and Decline is a poem in the pre-Qin period. With rhetorical devices such as rhetorical question, argot and intertextuality, the expression of emotion turns to emotion. Re-chapter and change words, and rhyme is harmonious. There are long and short sentence patterns, strong sense of rhythm, harmonious and beautiful rhythm and extremely delicate words. Decline has also become a common image in later poetry, which has a far-reaching impact on later classical poetry.
References:
Baidu Encyclopedia-The Decline of National Wind in Lang Feng