It was written on demand for the Norwegian Broadcasting Corporation (NRK) and survived a fire in 1970 by being kept safe in their archives.
It is built on a Norwegian legend about the sea-creature nøkken, and is based on a story about him transforming into a beautiful, white horse and getting out of a silent pond.
The horse lures a young boy onto its back and takes him with it back into the pond, generating a great disturbance in the normally so silent water.
Nykken (Norwegian) or Näcken (Swedish), originating from Old Norse, is a spirit said to exist along the borders of water and land.
People would often say prayers to the Nykken before swimming so that no harm would come to them.