There are also letters referred to by Hongyan. Everyone is familiar with the allusions of Hongyan biography, and the application of Hongyan as a messenger in poetry is also very common. For example, "Wild geese don't answer me, rivers and lakes are full of rain", "Shuo Yan sends books, and Huang Xiang shed more tears".
Goose habits
The wild goose is one of the well-known birds. When migrating, dozens, hundreds or even thousands of geese always gather together and fly in a line with each other. The ancients called them "strict array".
The "Yan Zhen" was led by the experienced "Touyan". When speeding up the flight, the team is arranged in a "human" shape. Once it slows down, the queue changes from "human" to "one", which is an effective measure for long-distance migration. The geese are composed of 6 or multiples of 6, and the geese are the aggregation of certain families or certain groups.