A variety of harmoniums populate Honoré de Balzac's novels, including the physharmonica, the orgue expressif, the panharmonicon, and the accordion. The sounds of these instruments typically illustrate unusual mental states. Balzac's musical fantasies drew on contemporaneous medical practice, which between 1820 and 1850 used the harmonium regularly to help treat nervous disorders. The linking of the harmonium with nervous effects resembles earlier associations of the glass harmonica with pathology. However, the medical implementation of the harmonium differs from this tradition both in the instrument's generally positive connotations and in the later trajectory of its use.
Studying the discourse of ethereal mediums helps explain why certain types of sounds were thought to have privileged access to the nerves. The unusual timbres and swelling dynamics of newly popular musical instruments, including the glass harmonica, the Aeolian harp, and the Jew's harp, were conflated with ideas about a vibratory nervous system and an ethereal world spirit. Both ideas were essential to the formation of the culturally determined ideal of ethereality in the eighteenth century. Closely linked to contemporaneous ideas about physiology and nervous transmission, the sounds and their presumed access to the nervous system continued to influence the design and reception of instruments, most notably the harmonium, during much of the nineteenth century.