The novel swings between a bright, sentimental, and excited tone when the narrator is describing the friendship and love growing between the inhabitants of Misselthwaite Manor, to a dark, mysterious, and Gothic tone in more somber moments. The tone of the novel grows gradually less dusky and serious as the personalities of the characters become more open, happy and free. At the beginning of the book, the tone is so mysterious and sober that it is almost frightening. By the end, it's so joyful and full of energy that it seems almost like a different novel.
The subject dictates the form in this novel to a high degree. Early in the novel, the narrator extols the virtue of "Yorkshire bluntness," in which people speak what is on their minds clearly and sometimes harshly. The narrator takes this approach to discussing the many faults of the principal characters, often calling Mary "sour," "dull," and "selfish" as well as implying that she has good qualities buried beneath her unpleasant surface. There are moments when the tone of the book is directed toward a very young reader, as Burnett's narrator explains concepts or gives the etymology of words in simple language. The voice of the narrator often feels deliberately educational or didactic, especially when the moral elements of Burnett's book are being "explained" to the reader. The narrator's attitude toward the benefits of moorland air, the county of Yorkshire and the friendship of country people is ecstatic and romantic. It also uplifts the Christian Scientific virtue of divine healing, instructing the reader to follow the example of Mary and Colin's betterment. The book vibrates with Burnett's enthusiasm for the glories of nature, and the tone is always lightest when characters are in locations of pastoral beauty.
Burnett uses Yorkshire idioms in several places in The Secret Garden to denote the response the people of Misselthwaite Manor and its surrounding area have to Mary Lennox. Using local idiom in this way allows the reader a glimpse into the mindset of the Yorkshire characters and allows the author to lend a bit of local color to interactions as small as thoughts. When Mrs. Medlock is bringing Mary home to the manor for the first time, she observes her discontentedly and makes use of the word "marred," which is a Yorkshire term that means spoiled and pettish:
Mary sat in her corner of the railway carriage and looked plain and fretful. Her black dress made her look yellower than ever, and her limp light hair straggled from under her black crêpe hat. “A more marred-looking young one I never saw in my life,” Mrs. Medlock thought.
The word "marred" is often spelled and used as "mardy" and connotes someone who is sulky or whining. Used in this way, however, it associates Mary's physical appearance with her unpleasant demeanor, as "marred" in standard English means "sullied" or "disfigured."
Fittingly, all the language Burnett uses to describe Mary in this segment is of ugliness and disorganisation. She is "plain and fretful" even when sitting still, with "straggling" hair that sits "limp" on her ugly dress. It would be hard to imagine a less sympathetic depiction of a young child by a narrator. The narrator in The Secret Garden, in this and many other parts of the first half of the novel, is tonally very unsympathetic to Mary. Burnett does this to engage her audience in Mary's selfishness and bad upbringing, and to make young readers think carefully about the choices she is making in her speech and behavior.
