Princess Irene is a dynamic character, who matures as the story progresses. During the course of the action she gradually, and at times painfully, learns that there is a supernatural reality beyond the observable world, a truer reality whose power is tapped by having faith in the unseen. In the first part of the story Irene struggles to convince herself that Grandmother actually exists and is concerned with the health of her soul. At first, Irene is frustrated because Lootie will not believe such a being exists, but later Irene herself begins to think the whole experience was only a dream. Midway through the story, Irene's faith wavers for the last time. One of the goblin's malformed creatures surprises Irene in her bedroom. Instead of going upstairs as Grandmother instructed, "her heart failed her" momentarily and she rushed foolishly outside where the goblins could catch her. Fortunately, Irene fights off the panic and returns to Grandmother, who pardons her because she has not done wrong "willfully." Afterwards she seems perfectly assured of her faith and, in fact, soon takes on a dangerous mission. She follows an invisible thread, spun by Grandmother out of spiders' webs, into the bowels of the mountain to rescue Curdie, who had been captured by the goblins. Thus, Irene uses her faith to help another.

Much to Irene's surprise she saw the loveliest room she had ever seen in her life!
Curdie's guide through the goblin caves is an ordinary ball of string, collected for him by his mother. This real string fails Curdie and he is captured by the goblins. By means of the magical thread, a token of her trust in Grandmother, Irene finds Curdie's jail and leads him out to freedom. Afterwards, when Irene takes Curdie upstairs to visit Grandmother, he does not have the ability to see her. He sees only "a heap of musty straw" where Grandmother's splendid furniture is. "Curdie is not yet able to believe some things," says Grandmother in order to comfort Irene.

In many ways Curdie is a familiar hero. Brave and resourceful, he cares for the welfare of others more than for his own safety. But he also has the unusual talent of making up songs to confound his enemy the goblins. As a natural poet, Curdie shows the value of an imaginative approach to life that relies on intuition as a guide through the maze of error and confusion. A valuable function of imagination is to keep the mind receptive to belief. Eventually, through tribulation and instruction, Curdie's faith develops to the point where he too can see Grandmother and use the invisible thread.

The goblins live underground, away from the light. They hate music and beings who are inventive. Their own minds are bent on revenge and domination. Paralleling the depravity of their minds, their bodies have become deformed. They are emblems of what becomes of people who have turned away from a spiritual life. However, their nasty wit, often exercised on each other, makes them interesting antagonists.

A compelling and mysterious figure, Grandmother is high above the sullen, earth-buried goblins. She demonstrates to people that there is a greater reality beyond the reality of this world. She has existed for hundreds of years, can change her form, has a marvelous lamp which can shine through walls—all evidence of her otherworldly nature. She is not a witch, however. Instead, her character is Christ-like. Her role in the story is to guide Irene lovingly, step by careful step, into mature belief. Along the way Irene grows out of her self-centered child's world and shows concern...