Much of the humor in the books is derived from the self-referential way in which the author acknowledges the unreality of talking animals, unlike other children's works in which they are accepted as normal. As the series progresses, the Bean Farm animals attain national fame for their ability to talk and read, and the humans whom they encounter are taken aback at first (though only momentarily) to find themselves conversing with animals. The animals and humans do not age, although the stories reflect the social conditions at the time of writing; for example, the books published during World War II feature scrap drives and victory gardens.