n 1837 Providence, some invalid women turned out, under hypnotic treatment, to have a sixth sense: they could see into the bodies of others to diagnose illness; they could follow unspoken mental commands; and they could read letters sealed in heavy envelopes by pressing the letters against their parietal bones. These events initiated the science of mesmerism, or hypnosis, in the United States, which would blossom into a major national movement (encompassing Spiritualist séances and mediumistic practices in the late century) and produce a series of compelling social-psychological theories. The talk offered a genealogy of the “sixth sense” of these early clairvoyants as a first step toward understanding the subsequent developments. Dr. Ogden argued that the sixth sense is sentiment. In a move that had antecedents in the eighteenth-century culture of sensibility, mesmerism reworked feeling, especially diseased or excessive feeling, into a source of empirical information about the natural world and the minds of others. The question is, what ways of imagining the social did this reworking make available?