What do the Iron bars symbolism tuck everlasting mean?

In "Tuck Everlasting," the iron bars symbolize the constraints of life and the boundaries that separate the eternal from the mortal. They represent the limitations imposed by society and the natural order, highlighting the tension between the desire for immortality and the acceptance of life's transience. The bars also serve as a metaphor for the characters' emotional and existential struggles, illustrating the idea that true freedom comes with the acceptance of life's impermanence.