Homesick, meritorious and ambitious, this is the mind of the ancients. However, when you are far away from your hometown and relatives for a long time, you will inevitably feel disappointed. Coupled with the inconvenient transportation and slow contact in ancient times, homesickness can be as long as a thousand miles. Moon, swan goose, double carp, mud coat, soup and perch have become the code words to convey homesickness. For example, Meng Haoran's "Early Cold Feeling", in the poem: the wood falls to the south, and the water is cold with the north wind.