From the object to the heart, it can be understood as "write other things first, and then draw what you want to say in your heart." The original meaning of the word "Xing" is "Qi", so it is often called "Qi Xing", which plays a role in rendering atmosphere and creating artistic conception in poetry.
The word "xing" in The Book of Songs is interpreted by Zhu as "talking about other things first, so as to stimulate what is sung", that is, paving the way for what is sung by other things.
It is often used at the beginning of a poem or a chapter. Sometimes when a sentence in a poem looks interesting, whether it is interesting can be judged by whether it is used at the beginning of a sentence or paragraph.
For example, in Feng Wei's self-protection, "Mulberry leaves are flourishing before they fall" means prosperity. About the most primitive "xing" is just a beginning, which has nothing to do with the following, but shows drift and association for no reason. Just like Qin Feng's Morning Wind, it is difficult to find a meaningful connection between the beginning "_ morning wind, depression in the northern forest" and the following "I don't see you, I am worried about you." Although in this case, it may be incomprehensible because of the time gap, this situation definitely exists. Even in modern folk songs, we can still see such "xing".
Besides, there are many meaningful uses of "Xing", such as metaphor, symbol and contrast. But it is precisely because "Xing" was originally produced by the drifting and association of ideas for no reason, so even if it has a more real meaning, it is not so fixed, but subtle.
For example, Guan Guan's novel begins with "Guan Guan's dove is in the river continent", which was originally used by the poet to lead to the following "My Fair Lady, Gentleman is Nice", but the harmony of Guan Guan can also be used to describe the courtship between men and women, or the harmonious love between men and women, but its metaphorical meaning is not clear.