The main theme of the novel is centered around Sal's loss and acceptance of her mother's death. The setting of her journey to be accept her mother's death is found in beautiful natural objects and places. Sal's understanding of her past is linked to the trees, fields, wildberries, and lakes. The great emotion that Sal and her grandparents experience is among the natural beauty of Lake Michigan, the Badlands, Old Faithful, and the mountains of Idaho and Montana, just to name a few. Sal and her family respect and appreciate nature, realizing what nature offers is a blessing that is priceless.
The title of the book refers to putting yourself in another's shoes in order to understand them, another theme seen in To Kill a Mockingbird. Sal is able to make sense of her own life only by walking in the shoes of her mother, her dad, Phoebe, and Ben.
Sal is even named after an Indian tribe and trees. She has much of her mother's "Indianness" in her appearance and in the ways she acts. Nature provides Sal with a source of comfort and strength throughout the book. She realizes her mother lives on through nature in the trees and birds.
The trees are especially important. They surround her mother's gravesite, and birds sing their beautiful songs in the trees. In the end, they help Sal accept her mother's death. There are three "singing" trees in the novel. The first one is in Kentucky, the second is in the tree outside the hospital in South Dakota, and the third is near her mother's grave in Idaho. They express Sal's powerful reactions to the natural world, but they also respond to her changing emotions. They symbolize the generosity of the natural world, responding to Sal's loss and grief. They may not always sing, but they are always beautiful and are a source of joy for Sal.
Blackberries provide Sal with another memory of her mother. They symbolize the bounty and generosity of nature and Sugar's (Sal's mother) desire to share her love of nature and its goodness with her family. Blackberries are the unexpected sweetness nature gives us, even when we are faced with tragedy and loss.