For all its fluffiness, this a song about death. The main character of the movie Watership Down, a rabbit named Hazel, is suffering from a gunshot wound from a farmer. His brother has to help and is called by the rabbit god of death. How can the light that burned so brightly, suddenly burn so pale?
When I was young I read the book, and I was fascinated. I was totally into it, and a recent remake of it on Netflix made me relive all that. It is still a beautiful story.
Writer Richard Adams said he hated the song.