The different meanings of "Yan" and "Yan" in ancient poetry!

Wild goose is a large migratory bird, which moves southward every autumn, often causing homesickness and wandering sorrow. Swallow is a migratory bird, which migrates with the change of seasons, and likes to enter and leave people's houses or eaves in pairs. It often appears in ancient poetry, especially favored by the ancients, with rich images: either cherishing spring and autumn, exaggerating sadness, pinning acacia, or sentimentalizing current events.