The primary theme of E. T. A. Hoffman's satirical novel is the central role of creativity in human life. The novel takes the form of two biographies, each concerned with a creative individual. While Hoffman specifically presents the theme of the centrality of music, he also uses the supposedly anonymous biography of Kreisler to emphasize creativity more generally. In addition, along with the relationship between creativity and humanity, he utilizes the character of the cat Kater Murr to convey a theme of the artist’s stance against social conformity: even though Murr is not actually human, he seems even more determined to live by his own rules than the musician Johannes Kreisler. Thus, through a nonhuman character, Hoffman can convey in exaggerated form his message about the importance of individualism.

Another important underlying theme, which the author uses to organize the book as much as he discusses it, is the importance of language. Hoffman experiments with a music-like structure with repeated motifs that appear in isolation or harmonize with others. He also merges two disparate narratives, those of Murr and of Kreisler, especially in highlighting contrasting character traits as counterpoints. Blocked communication through language differences—and the ability to overcome those differences—represents both individuals and classes; these are represented by feline contrasted to human as well as to canine, as when Murr learns to understand Ponto the poodle.

The musical theme that connects various layers of the work is important both as it stands for creativity and for the ways the author uses it to advance characterization along with plot. Music is important in the characters’ lives, and songs are used to mark significant events they experience. Music especially represents Kreisler: not only is he often singing, but other characters also refer to his musical compositions. Music also helps the author express the elemental desires, including sexual ones, that the characters cannot otherwise express.