Life and Death
The opening outlines the juxtaposition of life and death, indicating that it is the overarching theme of Skellig: Michael introduces the doctor treating his critically ill sister as "Dr. Death" because of his pale complexion, which does not sound reassuring and leaves doubts as to whether his sister will survive. He mentions Skellig, whom he found in the garage, thinking he is already dead because he is covered in dust, cobwebs, and dead flies. At the same time, however, there are hints at renewal and life after death, as Michael's family has moved into a new house just in time for spring, a time of renewal when nature comes back to life. Moreover, the fact that Skellig has seemingly been in the garage forever suggests that he is above the cycle of life.
The tension between life and death is most prominent in the baby's constant struggle for survival. Michael and his parents never know for sure whether she will recover, which puts an extraordinary amount of stress on them. Tubes are taken in and out of her tiny body depending on her condition. In fact, several events seem to foreshadow his sister's death: When Michael sees his sister at the hospital, he describes her face as dead white and her hair as dead black. On the day of her heart surgery, he claims to have lost track of her heartbeat, which makes him think she has died. At this point, Mina's mother cuts open a pomegranate, a symbol of life, and tells the ancient Greek tale of Persephone, who leaves the underworld after the months of death, reintroducing the theme of revival. Indeed, against all odds, Michael's sister comes back to life after her heart has stopped for a short moment, and eventually, Michael's family is assured that the threat of death is gone. With the help of Skellig, death has been defeated.
Homeschooling vs. Formal Schooling
Through Mina's character, Almond presents a series of strong arguments for homeschooling. Mina is homeschooled and educated by her mother. She firmly believes that formal schools inhibit the natural curiosity, creativity, and intelligence of children, saying that the mind needs to be free and open instead of being shut in a gloomy classroom. Her thoughts are guided by poems of William Blake, who was a free spirit himself. In contrast, the teachers at Michael's school try to get everyone in line, implying that regular schools do not value individuality and personal expression. For example, Rasputin (the Science teacher) asks the students to lift their hearts and sing out loud in assembly, and the Yeti yells at them to keep to the left in the corridors.
Almond also criticizes the curriculum and instruction of regular schools. When Michael and Mina talk about evolution, a topic that Michael is learning about at school, Mina knows much more about it than him. She tells him about the evolution of birds, the development of bones, and the earliest fossil of a bird, the Archaeopteryx. She also teaches him the concepts of pneumatization and ossification, which Almond uses to prove that homeschooling does not necessarily mean a lack of academic rigor. In fact, Mina despises the idea of focusing on one subject at a time. She tells Michael that, while he is studying Science by completing mindless exercises such as filling gaps on worksheets, she is drawing, painting, reading, looking, feeling and listening; in short, she is opening her mind instead of answering closed questions. Moreover, she questions the use of categorizing readers based on their ability, suggesting that every student should be free to choose what they want to read.
However, one argument in favor of formal schools stands: Because homeschoolers learn in solitude, they lack social skills. In Chapter 29, Michael accuses Mina of being so high up in her own spheres that she does not know anything about "ordinary people" like his friends at school.
Nurturing and Care
The theme of nurturing and care appears in various places in the novel. The principal idea is that emotional nurturing can significantly improve someone's life. The most obvious example of this is Michael and Mina caring for Skellig. While the homeless man is at first reserved and calls himself "Nobody," he gradually opens up after being nurtured by the two children with Chinese food, beer, aspirin, and unconditional love. Similarly, he is supported by the owls bringing him food. At one point in the story, Mina observes birds working tirelessly to bring home food for their chicks, which resembles the dedication of the children caring for Skellig. Eventually, due to the nurturing and care, the homeless man believes in himself again, defeats arthritis, and gathers enough strength to save the baby's life.
Other characters show a lesser degree of care and are therefore less effective in their endeavors. For example, Dr. Death cares for Michael's sister on an entirely physical level and does not get involved on an emotional level, unlike Michael, who is so worried about her that he gets up at night to check up on her breathing, making sure she is healthy. Other doctors at the hospital are equally ineffective because of their lack of empathy, which leads to Michael's sister almost losing her life on the operating table. Another example is Mrs. Dando: When she sees Michael being sad, she also cares only on the physical level and offers him fruit gum. However, he rejects it because he is so depressed by the recent move and his sister's critical condition that a simple piece of fruit gum is not enough to soothe his inner pain. He finds support in his family, with his father giving him coke, sandwiches, and Chinese food (physical care), and his mother offering emotional care—e.g., by touching his arm when she talks to him.
Finally, the theme of nurturing is apparent in Mina's cognitive development, which seems to be much faster than Michael's. While Michael does not seem to retain much of what he has learned at school because the teachers do not care for their students, Mina is constantly challenged and nurtured by her mother, who allows her to learn with all her senses, which leads to a deeper understanding of the world. Mina passes her knowledge on to Michael and nurtures his mind as well. Eventually, he adopts her thinking (he sings along when she recites one of Blake's poems) and says he is ready to care for his baby sister.
Coming of Age
The novel doesn't depict a pure coming of age, but Almond subtly interweaves this theme into his work. Michael and Mina are still children and do not physically age a lot, but they are, as Don Latham writes, in a "kind of liminal territory." Furthermore, Almond heavily uses William Blake's Songs of Innocence and Experience to support how Michael and Mina vacillate between childish pursuits and emotions and wiser ones more characteristic of adulthood. Latham explains that the children's "ability to discern Skellig's extraordinary nature and their willingness to accept responsibility for his well being both reflects and facilitates their own passage from childhood to adulthood, and it is their passage through this liminal territory—these merged realms, if you will—that is the real focus of the novel."
Faith
Faith isn't conceived of in the religious, especially orthodox, sense—rather, the young characters of the novel exhibit faith in the wondrous: faith in the things that don't make sense—the things that perplex and disturb them. If adults saw Skellig in the garage, they would no doubt have a fit and call the police immediately; Michael, in contrast, only wants to help. If adults saw Skellig's wings, they would immediately try to figure out what he was, dragging him to doctors and scientists. For Michael and Mina, though they are curious, the only thing that matters is that Skellig grows to be happy and healthy. Almond teaches his young readers to have faith that there is magic and beauty in the world, even when it doesn't quite look like what you expected.
Change
Young Michael has undergone a great deal of change right as the novel starts, and he will continue to experience more. He has to come to terms with an ailing baby sister, a new house, distracted parents, changing relationships with his friends, and the entrance of two new extraordinary beings into his life: Skellig and Mina. Almond suggests that change can be hard—Michael cries a lot and is occasionally angry, quiet, or confused—and that it is okay not to react to it perfectly, as long as you are aware of how you are interacting with other people—e.g., Michael's fights with Mina and his Dad, both of which he is able to apologize for. Almond writes that change takes time to come to terms with, and it might not bring about exactly what one expected; however, change may, if one is patient, be even more wonderful than you expected.
Ambiguity and Lack of Closure
After a reader finishes the novel, they still don't know exactly what Skellig is, nor how he came to be in the garage, nor his role in healing the baby. These are mysteries Almond chooses to leave unsolved because, for him, mystery has an important role in storytelling. Much of what is wonderful in the world resists easy answers, and seeking answers can make us miss out on what is happening. It is more important that Michael grow in his compassion, patience, and wisdom than it is for him to find out what exactly Skellig is.
