"The Lion and the Mouse"
Once upon a time, in a jungle, there lived a fierce lion. One day, while he was sleeping, a little mouse accidentally ran over his paw, waking him up. The lion, angry and annoyed, caught the mouse and was about to crush him. The mouse begged for mercy and promised to help the lion someday. The lion laughed but let the mouse go. A few days later, the lion got trapped in a hunter’s net. He roared for help, and the mouse came running. The mouse chewed through the ropes and set the lion free. The lion was grateful and realized that even a small friend could be a great help.
What is the main theme of the story?