Mary stares at the key for a while, thinking that if she could find the door, she could see what's inside. She's curious about what it looks like after being neglected for ten years and thinks that she could go inside, shut the door, and play alone. Life at Misselthwaite has made her imaginative and curious for the first time; it was too hot in India for her to think about anything. Mary puts the key in her pocket and walks up and down the wall. She finds it frustrating to be so close to the secret garden but unable to get in, and decides to carry the key with her everywhere from now on, so if she ever finds the door, she'll be ready.
Again, Mary's curiosity about the state of the garden mirrors her latent curiosity about how alive she is on the inside. The fact that the narrator notes that she's already becoming imaginative and curious offers hope that the garden is alive enough to be of interest, and that both will continue to grow and develop. Keeping the key also allows Mary to feel as though she has her own secret, which in turn helps her feel independent.
Martha returns the next day with stories of her day out. She and Mother washed and mended clothes and baked good things to eat. The children all liked hearing about Mary, and Mary tells Martha that she'll tell her more about life in India so that next time she goes home, she'll have more to tell them. Mary asks if Dickon and Mother liked hearing about her. Dickon apparently was intrigued like the rest, but Mother seemed sad that Mary was alone with no one to cheer her up. Very seriously, Mary tells Martha that her talking does cheer her up.
When Mary admits that Martha cheers her up, it shows that Mary now recognizes that Martha is a person who can bridge the gap between adult caregiver and same-age friend. This in turn helps Mary learn how to accept the authority of other adults going forward, while it also gives her practice in how to converse in a meaningful and polite way with someone.
Martha leaves and returns with a present for Mary, courtesy of Mother: a jump rope. Having never seen one, Mary wants to know what it's for. Incredulously, Martha picks up the rope and starts to skip in the middle of the room. Mary is transfixed, and when Martha stops, Mary feels excited. Martha hands over the rope and assures Mary that if she practices, she'll get better. She also says that Mother believes a jump rope is the best thing for Mary.
Feeling gleeful and excited about the jump rope makes it clear how far Mary has already come—while she was a languid child in India and wasn't interested in the outdoors only a few weeks ago, now physical activity is something that intrigues and excites her. Jumping rope also allows her to be outside, where she can breathe the fresh air and continue to grow, which may be why Martha’s mother believes a jump rope will be so beneficial for Mary
As Mary heads outside, she stiffly thanks Martha for the jump rope and holds out her hand. Martha shakes it, laughs, and says that if Mary were one of her sisters, she'd kiss her in thanks. In an even stiffer voice, Mary asks if Martha wants a kiss, but Martha just laughs and shoos Mary out.
Thanking Martha and offering, albeit uncomfortably, to kiss her, indicates that Mary is beginning to recognize that other people have a choice in whether or not to do nice things for her—people aren’t just going to cater to Mary by default. Though Mary’s words of thanks are stiff, this moment shows her developing sincere gratitude and humility.
Mary wanders through the gardens, skipping and counting. She skips to Ben Weatherstaff and he comments that the skipping is putting red in her cheeks. Mary is thrilled. Ben encourages her to keep skipping and notes that the robin will certainly follow her again today. Mary skips off to her favorite path along the ivy wall. As she skips, she feels the key in her pocket and with a laugh, asks the robin to show her where the door is. He just sings at her.
Ben's comment about the red in Mary's cheeks suggests that nature has a healing effect on her. As Mary has only just started skipping rope and already looks heartier and healthier, this passage also indicates that nature works quickly to help someone feel better.
The narrator explains that Mary will go on to believe that what happens next is the work of Magic, which she first heard about in her Ayah's stories. A gust of wind blows the ivy where the robin is sitting, and as it moves, Mary catches the vines, having seen a doorknob underneath it. She starts to pull the ivy aside and reveals a door with a lock. Fishing out her key, Mary finds that it fits perfectly in the lock. Mary checks that nobody is watching before she turns the key, pushes the door open, and slips quietly into the secret garden.
The robin's place in this discovery shows Mary that the natural world and animal friends will do as she asks if she treats them kindly and with respect. She asked the robin to help her in what's described as a kind and pleasant voice, which then helps Mary to learn that engaging with someone pleasantly will get her further than short, abrasive commands.