What is the symbol of novel medicine walk?

The color purple is a recurrent symbol throughout Medicine Walk. When Jimmy is shot, the mud around Jimmy is made purple by his blood. Frank sees purple in the night sky above after Eldon discloses the story of Jimmy's death. When Eldon craves a drink after the thought of losing Angie to Bunky, there is a "purple ache" between his ribs. Purple often appears in Wagamese's descriptive language around loss, and so purple often functions as a symbol for loss throughout the novel.

When Eldon builds Bunky's fence, the earth beneath Eldon is hard and unrelenting. When Frank digs Eldon's grave, the earth is similarly implacable. Eldon gets sober while digging Bunky's fence and working the earth, and so the "hard, unrelenting" earth during these chapters is a symbol for Eldon's journey to sobriety. When Frank digs a similarly unyielding ground, the earth comes to symbolize coming to terms with familial hardship. Eldon and Frank both succeed in completing their respective jobs, but not without struggle. In much the same way, Eldon is able to come to terms with his drinking problem, and Frank is able to come to terms with his father's troubled history, but not without struggle.