My father read this to my brother and I when I was in Kindergarten or first grade. I do not recall much about the story. I mainly remember sitting on the couch and my father smelling the new-ish book and commenting on it. He was wrong that book smelled weird and did for years afterward.
I enjoyed this story quite a bit. Anthropomorphic animals are almost always fun.
Mole is doing some spring cleaning in his subterranean home. He gets a sudden urge to leave. He digs his way out and excitedly starts trundling his way through the woods. At one point a a rabbit tries to stop Mole, demanding that Mole pay a road toll. Mole bustles past crying out, "Onion-sauce! Onion-sauce!"
After a short time Mole meets Rat. Rat is a water rat and very friendly. Rat invites Mole over to his place and Mole ends just staying there. Mole and Rat have some adventures. We meet the the feather-brained and self-important Toad who falls in love with dangerous motor cars. Somewhat grouchy Badger comes in and plays host to a lost More and Rat and later works to straighten out the misbehaving Toad.
Everything is in good fun with adventure and humor. According to the Internet Box Grahame retired from his job at ended up writing the stories he told his son years ago. I suppose these are the same as any other parent stories: you tell a somewhat silly tale and figure to throw in some talk about proper behavior.
Grahame either coined or popularized the phrase "there is nothing—absolute nothing—half so much worth doing as simply messing about in boats." I recall hearing another phrase that is still in use, but alas, I have forgotten it.
--Oh! I just found it "Piper at the Gates of Dawn" I'm not sure if that originated with Grahame though. Look it up yourself.
1. When in grad school I had to do a research paper in my History of Children's Literature class. I chose artist and illustrator Arthur Rackham whose work and style are still unique and immediately recognizable after 100 years. Rackham was a perfectionist and was literally on his deathbed when he finished an illustration for Wind in the Willows by adding in the oarlocks on Rat's boat that Rackham forgot to draw on his first draft. Or, maybe it was the oars.
2. I've not seen the Terry Jones film adaptation but the two minute trailer I saw online shows it to be fairly awful. I'll have to see if I can watch it through a streaming service.