Li Yu felt that his ruling mistakes led to national subjugation, and he was ashamed of his ancestors and nationals. Therefore, "the old country can't bear to look back at the bright moon." Moreover, he resisted first, and then surrendered. Song Taizu tried to scare him and humiliate him in various ways. Li Yu, a talented person, has been emperor for so many years. Now he is the king of national subjugation, and his dignity is swept away. Naturally, he felt that the days were like years. This word combines his shame and yearning for his old country, his recollection of his past life, and his pain and gloom in prison now.
It is a bit wrong to say that the author died in his later years. Li Yu did not die of natural causes. He was poisoned in his prime, not to mention his works in his later years. His works should be based on the boundaries before and after the national subjugation, and all the masterpieces handed down from ancient times were imprisoned after the national subjugation. It is really "poetry must be poor, and the merits are behind."