The swans return song to the gods, and larks return song to the world.
This story is from Lord Dunsany’s Fifty-One Tales, originally published in 1915, and is read aloud by Kay Mack.
You can read the story here, or online at: http://www.gutenberg.org/ebooks/7838
“The swans are singing again,” said to one another the gods. And looking downwards, for my dreams had taken me to some fair and far Valhalla, I saw below me an iridescent bubble not greatly larger than a star shine beautifully but faintly, and up and up from it looking larger and larger came a flock of white, innumerable swans, singing and singing and singing, till it seemed as though even the gods were wild ships swimming in music.
“What is it?” I said to one that was humble among the gods.
“Only a world has ended,” he said to me, “and the swans are coming back to the gods returning the gift of song.”
“A whole world dead!” I said.
“Dead,” said he that was humble among the gods. “The worlds are not for ever; only song is immortal.”
“Look! Look!” he said. “There will be a new one soon.”
And I looked and saw the larks, going down from the gods.