How does the author use symbolism in the novel, With You and Without You?

The author uses the presence of ashes to symbolize Liza's fear of death. At the end of Book II, after the memorial service, Liza goes home and burns a copy of her father's obituary in the bathroom sink. In Book III, we learn that ashes have become a "problem" for her. Her father had been cremated, and she explains, "I saw ashes and I thought of death. It started, not the first time I saw the pot in the funeral home, but later, that time when I burned my father's obituary. I looked at the ashes as the tapwater washed them down the drain, and I kept thinking, 'They're like flakes of Dad, flakes of Dad, flakes of Dad.' "