Once a doctor, who works at the museum, was walking along the bank of the river Thames in Chelsea. Lots of creative people live in Chelsea and many of them prefer houseboats. They enjoy living on the water. It inspires them and they draw pictures. When the doctor was looking at the houseboats, he noticed a freshly painted small boat called Nerine. A young lady owned this boat. She stuck in the hole and couldn't push back the cover because of the fresh paint. The doctor helped her get out on the deck. They became friends. The lady was quite unusual. She had a pseudonym "Thetis". She lived together with two fishes and an octopus on the boat. Sometimes Thetis would sit near the aquarium and imagine that she lived on the bottom of the ocean. The girl sang a sad song to the doctor. Its title was "The Silver Swans". In this song she asked how she could recognize a true love.