Nature
Nature plays a considerable role in shaping the events of the story and its characters. The world of the Yorkshire moor—a land of pure, free nature—is very influential in bringing life back to Mary, whose budding love for nature is said to “blow the cobwebs” of apathy from her brain. Nature is what joins Mary together with new friends Dickon and Ben Weatherstaff, who work together to enliven the secret garden. Nature, more specifically the gardens, also serves as the meeting grounds for Mary and Colin to form a powerful alliance that ultimately delivers great healing to the entire Craven household.
Throughout, a connection with nature is equated with wisdom and well-being. For example, Dickon's deep knowledge and communion with the plant and animal kingdoms is directly correlated with his compassion and kindness towards other humans. Colin's venturing into the gardens is shown to completely heal him from his conditioned malaise. We also can infer how the outer nature of the flora and fauna aids the characters in remembering their own inner nature that has been suppressed. Thus, nature is seen as the main life-giving force for people to transform into their true selves.
Magic
In many ways, The Secret Garden is a story about encountering the magic of life. Many of the characters have dealt with heavy circumstances—the death of Mary's parents, Colin's illness, the loss of Mr. Craven's wife—and yet all come to recognize that not all is hopeless through the magical workings of the world around them. This is best illustrated when Mr. Craven, while sitting by a river, suddenly and inexplicably feels an uncharacteristic sense of peace that ultimately brings him back home to reunite with his son.
Colin is interested in magic as something more quantifiable and controllable, such as the way he leads the others in chanting mantras to affirm the magic inside of them. Yet we eventually come to see that magic lives most powerfully through the little things, such as the instance when the robin shows Mary the key to the garden, or how the roses thrive in the garden despite years of neglect. This is the magic of life itself, what makes the plants in the garden grow and the sun rise each morning. Towards the end of the book, Mrs. Sowerby, Dickon's mother, describes magic as the “Big Great Thing,” presenting an image of magic as God or the great force that lies behind all movements in nature.
Secrets
The manor of Archibald Craven is shrouded in many secrets—that of Mrs. Craven’s death, of his son Colin, and of the garden itself. When Mary first arrives, she must navigate her way through all of these secrets, demanding to know the truth where others, such as the servants, have become willing to hide those things which Mr. Craven can’t face. We are shown how keeping painful memories hidden is a way Mary’s uncle deals with his grief; with the garden locked up, for example, it is easier to pretend that everything is fine and that the death of his wife never happened. Yet we are also shown how these secrets are ultimately very destructive—by preventing Mr. Craven’s true ability to heal as well as by bringing others, like Mary, into the illusory reality he wishes to maintain. Mary is the prime force for uncovering these secrets and helping her uncle to see that by confronting the pain of the past, new life and new hope can actually emerge.
Rebirth
The strong presence of nature imagery in the book runs parallel to the theme of rebirth and reawakening of life that has been hidden or suppressed. We find Mary first at the manor during winter, when the plant life is more barren. The arrival of spring coincides with her steady transformation from a sour little girl into a carefree child who rallies others to also find their own happiness. By connecting to the natural world, Mary is able to see her real self beyond the mask of apathy she wore while in India. Thus, the book suggests how all beings have an essential nature that can reemerge even after the most traumatic of experiences.
Almost every character in the book experiences some sort of profound change where they shed their former identity for a sense of self that is better and more alive. For example, Colin has always believed he is sickly and disabled, only to realize that this has been mostly an illusion of the mind, and that underneath this role he is actually a vibrant and creative boy. We even see how Mrs. Craven lives on through her garden, especially her favorite rose plants, as well as through her son. In this way, we are made to understand how nothing ever truly dies but is rather constantly being reborn through the cycles of life.
Childhood
Neither Mary nor Colin grow up in a very healthy way, where they can truly live out their childhoods. Mary was ignored and neglected by her family, given everything she wanted and spoiled by her servants—not out of love, but out of fear that she would cry and disturb her mother. This is paralleled by Collin, who grew up being similarly pampered by his servants under the assumption that he was deathly ill and couldn't go outside to play like a normal boy. The first thing that Mary and Colin bring to each other is a fellow child who can understand each other and form a true bond, finally embracing the childhood they never knew. Their frequent games, laughter, and enjoyment of nature help return to them a sense of innocence and wonder that is so essential for children to grow into mature and happy adults.
The Power of Belief
Repeatedly in the book the theme of belief is emphasized. This is most obvious in the development of Colin, who has been fed the belief for his whole life that he is ill and beyond help. Mary assists him in seeing that his sickness is mostly created through the mind, and that when he stops worrying about dying or becoming a hunchback like his father, he feels in much better spirits. We can see how the approach of his doctor and nurses, while perhaps well-intentioned, is only reinforcing Colin’s illness by always identifying him as a patient and telling him he must rest and not go outside. The image of himself as being on the edge of death does not allow Colin to heal nor understand how his health is predicated on his own thoughts and feelings.
The power of belief is often equated with magic by Mary, Colin, and Dickon. They see magic as the ability to realize the underlying goodness of life and focus their thoughts in a positive way. By holding a sense of hope as well as a deep appreciation for nature, the children feel that they are being protected and guided by a benevolent force.
Class Differences
When Mary has to suddenly leave India, she is transported into an entirely different social world. Although she is still part of the elite class at her uncle's Yorkshire manor, Mary becomes surrounded by servants and friends who do not have the same docile attitude as her nanny in India. In her old home, Mary was completely indulged and seen as belonging to a very superior class that must be obeyed. In England, Mary becomes integrated with the local people, especially the peasant family of her maid, Martha Sowerby. This transition humbles Mary, bringing her to realize that it is not desirable to be put on a pedestal by those around her. By opening her heart to all people, regardless of their class background, her world expands and she makes her first real friendships.
