1) Use Hongyan to refer to the letter, or entrust Hongyan to deliver the book to express homesickness. For example, the folk song "Xizhou Qu" written by Yuefu in the Southern Dynasties said, "If you don't remember Mandy, you will look to Hong Fei".
2) Hongyan is a migratory bird, migrating in spring and autumn. In autumn, geese ride the long wind and fly to the south for the winter. This scene often affects the homesickness of wanderers. In ancient poetry, literati often express their feelings with geese, expressing the homesickness and sadness of wanderers. For example, Xue Daoheng, a native of the Sui Dynasty, wrote: "People return to yan zhen and think before spending."
3) Hongyan migrated in the Spring and Autumn Period, wandering and helpless all her life, so poets often use it to describe the desolate and miserable feelings encountered in life. For example, Wang Wei's "Going to the East" is "collecting Peng and returning to the wild goose."