Tuck tells Winnie about the wheel of life . What is the wheel of life, and why is it important?

The wheel of life is our lives.... the way our lives revolve from beginning to end.... the way nature replaces one part of the wheel with another life, and then another. Tuck admits to Winnie that he and his family aren't a part of the wheel..... their stuck in time. He wishes he weren't immortal, and that he were a part of the wheel.