Gliding of the Swans

This story is entitled as "Gliding of the Swans" because it depicts the swans' movement on the lake. They do it smoothly and gracefully. However, we don't see how much effort they exert to appear so beautiful on the vast and never viscous surface. We can't see how hard they move their feet under the water. Just like the main characters in this story, they might look perfectly fine outside but no one knows their battles inside.