Phrenology, a science centered on discovering and exploiting correlations between the shape of a person's head and that person's personality and intellect, enjoyed incredible popularity among Americans throughout the nineteenth century. Franz Joseph Gall (1758– 1828), a Viennese physician, created what others would later call this “science of the mind.” Gall argued that the brain could be separated into 37 different “organs,” all of which corresponded to a different mental faculty, such as “spirituality,” “self- esteem,” “hope” and “destructiveness.” He believed that one could identify every person's strong and weak organs by the shape of his or her head and then move to improve areas that were underdeveloped and take advantage of a person's natural gifts. It was a highly optimistic system that promised tremendous self- improvement based on rigorous self- examination and discipline.

By the 1830s, more than forty phrenological societies had been established in the United States, and by the 1850s even the smallest American towns had been touched by a frenzied interest in the possibilities of phrenology. “Bump doctors” traveled the countryside lecturing, selling phrenological books and tracts and analyzing the heads of all willing to pay their fees. Countless Americans applied phrenology to the most practical matters of their lives, from choosing a mate to picking a career.

The most successful popularizers and educators of phrenology in America were members of the Fowler family: Orson, Lorenzo, Charlotte, and Charlotte's husband, Samuel Wells. Among the earliest traveling phrenologists, Orson and Lorenzo crisscrossed the country, promoting phrenology through their writings, lectures, and consultations. Among the more famous heads they analyzed were those of John Brown, Horace Greeley, Walt Whitman, Mark Twain and Clara Barton. They eventually stopped traveling to establish the American Phrenological Institute in New York City, edit the country's first phrenological magazine, American Phrenological Journal, and work on a host of other phrenological projects and writings. One of their most famous works was The Illustrated Self- Instructor in Phrenology and Physiology. First published in 1840, it proved to be one of the century's most popular self- instruction manuals, going through more than twenty editions in the next fifty years.