In this children's novel, kindness is shown in many ways, illustrating the theme that being kind is an extremely important value. It keeps the world running smoothly.
Although the children's father is falsely imprisoned, and the mother and children forced to move from their home to live far away and in poorer circumstances, they find much kindness as they watch the trains go by at the station.
The Old Gentleman they always see on the 9:15 train is kind to the children and their mother, even though he doesn't know them. When he finds out from them that their mother is sick but can't afford to buy all that the doctor has ordered for her to get well, he sends a hamper filled with everything she needs. He sends a note saying the following:
here are the things you want. Your mother will want to know where they came from. Tell her they were sent by a friend who heard she was ill. ... I hope she will forgive me for taking the liberty of allowing myself a very great pleasure.
We learn from his note that kindness brings joy to the giver as well as the recipient.
The Old Gentleman shows his kindness, too, in sending Mother extras, such as peaches, chicken, port wine, roses and lavender water. A much more important act of kindness he performs, however, is looking into their father's situation of wrongful imprisonment and helping to get him freed.
The children themselves perform acts of kindness. For instance, they win over the surly bargeman, when they bravely save his baby from the burning boat. Near the end of the book, they also help Jim, who has broken his leg and is lying in pain in the railway tunnel. Bobbie stays with him in the dark and the cold as the other two children run to get help. Bobbie shows her kindness when she says of Jim's broken leg:
I'm afraid it's hurting you most awfully, Jim. I AM so sorry.
The children know that their mother, whose heart is kind, will take in Jim and nurse him, which she does. None of them know yet that Jim is the Old Gentleman's grandson, but through caring for him, they are able to help return some of his kindnesses without realizing it, showing that what goes around comes around. In this book, kindness pays forward: people behave kindly and when their need comes in turn, are treated with kindness.