In 1837 Providence, some invalid women turn out, under hypnotic treatment, to have a sixth sense: they can see into the bodies of others to diagnose illness; they can follow unspoken mental commands; and they can read letters sealed in heavy envelopes by pressing the letters against their parietal bones. These events initiate the science of mesmerism, or hypnosis, in the United States, which will blossom into a major national movement (encompassing Spiritualist séances and mediumistic practices in the late century) and will produce a series of compelling socialpsychological theories. The talk offers a genealogy of the “sixth sense” of these early clairvoyants, as a first step toward understanding the subsequent developments. Dr. Ogden argues 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?