The main theme of this story is-artistic freedom. The author says that real artistic work can only be done in the state of the perfect freedom. The Nightingale could sing well because it was free and roamed about in fresh air. Princess September never kept this bird in a cage, but, due to the brainwashing of her sisters, she locks her bird friend up in a golden cage, which the bird didn't like. Princess September forgets that every living creature has the right to live. the Bird feels sad and does not sing well. One day, September finds the nightingale lying still in it's cage and takes it out. There, the birds tells her that it cannot sing to her unless it is let free. Princess September lets the nightingale free . From then on, the nightingale sings to her everyday. This is how artistic freedom is highlighted in this lesson.