Describe symbolism in The Neverending Story by Michael Ende

In the opening chapters, the Swamps of Sadness in which Atreyu and Artax must traverse symbolize the utter hopelessness of depression. When Artax gives into the hopelessness and dies, Bastian cries bitterly. Morla the Aged One symbolizes the next stage of grief. Morla is tired of life and no longer cares about anything. Yet the hero Atreyu calls her bluff; he makes her realize that her lack of caring is feigned. Morla merely pretends not to care and acts cynical because she is lonely. In this way she, too, represents an aspect of Bastian. Atreyu's Great Quest to find a cure for the Empress is also, in symbolic terms, a journey towards healing for Bastian.