The Little Engine That Could by Watty Piper, 1930.

A little train is pulling a load of things for children over a mountain. The train is carrying toys of all kinds and also good, healthy food for the children.

Unfortunately, something goes wrong, and the engine pulling the train breaks down. The toys aboard the train know that the children over the mountain are waiting for them and that they will need the food on the train, too. Other train engines pass by, and the toys try to get them to help pull the train.

However, even though these other train engines are not currently pulling loads of their own, each of them has a reason why they cannot help to pull the train with toys and food for children. One engine is old and doesn’t think that he’s strong enough to pull even this small train. The bigger, stronger engines think of themselves as being too important to pull this small train because they handle more important things, like passenger cars or freight for adults, not children.

The toys are despairing, but then, a small blue engine comes along, and they ask her if she can help them. At first, the little engine isn’t sure that she can help because she is only a small engine and has never been over the mountain before, but the toys explain how important it is to get the toys and food to the children, so the Little Engine agrees to try.

As the Little Blue Engine pulls the toy train over the mountain, she gives herself positive self-talk, telling herself “I think I can-I think I can.” When she succeeds in her mission, everyone is happy, and she says, “I thought I could!”

This classic picture book is often used to show children the benefits of positive thinking and being willing to try. Instead of focusing on doubts about herself or reasons not to try, the Little Blue Engine makes the decision to try and tells herself that it’s possible for her to succeed. The Little Blue Engine doesn’t know if she can accomplish the mission (she “thinks” she can, although she doesn’t “know” if she can), but when she is willing to try, she discovers that she actually can. Even though she is small and seems less important than the bigger trains, she accomplishes more because she is willing to do what the bigger trains will not, taking part in something that is outside of her basic, required job. I also like how the book shows that it is sometimes the small, less prestigious tasks that make the biggest difference. Taking food and toys to children doesn’t seem important to the big trains, but it matters to the children and their families over the mountain.

However, this is not the first form of this story. The story of the little train engine that is able to go over the mountain because it thinks it can is actually based on an earlier form of the story that was originally part of a sermon from the early 1900s.

The book is available to borrow for free online through Internet Archive (multiple copies). There are also different cartoon versions of the story.