How is Cole's inability to choose a carving for the bottom of his totem a sign of maturity?

The bottom spot on Cole's totem remains blank for a long time. Cole has planned to carve something significant in that spot but he can't figure out what that will be. This seems to weigh on Cole as he tries to make the decision. The fact that he leaves it blank for so long is a sign of his emerging maturity which is an important part of his continued path toward healing, one of the story's themes. Cole's efforts to take this so seriously is a positive move and is a dramatic change from his childish arguments and tantrums of the previous year.