Through Franny Glass's spiritual breakdown, J. D. Salinger explores issues in not only mysticism and religion but also family, celebrity, education, and intellectualism. Of course, the religious themes are important: By the end of the "Zooey" section, Salinger seems to have arrived at a spiritual doctrine, to be followed by many of his characters. Zooey Glass passes along the teachings of their older brother, Seymour, telling Franny that she should respect and honor all human beings even if she does not always like them. It is this concurrent lesson of Franny and Zooey that makes the narrator, Buddy Glass, comment that the story is about love as much as it is about spirituality--for what this doctrine asks of its subscribers is love for all humanity.
Love is also a crucial element in the family relationships in Franny and Zooey. In the Glass family, the children are much more gifted and intelligent than the parents. But the children keep reminding each other that their parents must be loved and respected for everything they are and everything they have given their children. Even beyond love, family itself is a crucial theme in these stories. Zooey tells Franny that they have become "freaks" because their brothers taught them too much too young. But what their brothers taught also helps Franny out of her spiritual crisis. Through Seymour's lessons and Zooey's impression of Buddy's voice, Zooey channels enough support to talk Franny out of her distress.
The Glass family is special not only because of its extreme intellectualism. In addition, all of the children were child stars on a radio talk show. Celebrity, therefore, also emerges as a subtle theme throughout the text. Broadly, the stories can be said to be about the results of being famous children. More specifically, Franny and Zooey must decide whether or not to stay famous (as actors) or leave the pursuit of fame behind.
Much of what sets off Franny's breakdown is her disenchantment with the experience she is having at college. She hates both herself and others for the egotistical behavior and phony conformity in which they all engage. This theme is central to many of J. D. Salinger's works but takes a redemptive twist in Franny and Zooey: The author seems to acknowledge that even such people, with their huge egos and weak individual wills, should be admired and respected for their humanity, if nothing else.