How is the garden a symbol for the human spirit in The Secret Garden?

The green shoots begin to shoot up through the earth at the beginning of spring.

Mary and Colin want to bring the garden back to life, so they do their best work.

The garden is dying from neglect, but it comes back to life when it is nurtured and cared for.

The roses have wound themselves around the old tree, and a robin has come to nest in the bushes.