What's theme of The Four Clever Brothers?

One major theme is coming of age. As the brothers go their separate ways, they each follow their own dreams. When they return to their father, their dreams are challenged, and each of the boys needs to dig down deep and find the courage to save the princess, use their intelligence and be more..... to see the princess safely returned to her father, and in the end, they must put away their petty jealousies and learn to be a family.

As you can see, family is another of the story's themes.