That the cuckoo came to be seen as a bird of sorrow probably first stemmed from its real habits in nature. But the human world, after all, gains its significance from human existence, so naturally in literary allusions how the cuckoo sings its sad song, and why, have become divorced from the cuckoo's real behavior.
杜鵑成為人們心中的怨鳥，最早的緣起或許與它實際的個性有關，但人的世界畢竟還是以人的存在而產生意義，典故裡杜鵑怎麼哀鳴、為何哀鳴，與杜鵑鳥真實的「舉止」自然有了落差。