SPIRITUALISM is a widespread and generally unorganized movement that arose in the United States at the end of the 1840s, was influential through the nineteenth century in the United States and elsewhere, and persists at the beginning of the twenty-first century. At its core is the belief that the living can conduct conversations with spirits of the deceased through a sensitive instrument (either a mechanical or electronic device) or a human medium.

Spiritualism's advent was occasioned by two events. The first was the publication of Andrew Jackson Davis's visionary cosmology and universal history, The Principles of Nature, Her Divine Revelations, and a Voice to Mankind, in 1847. The second was the production of audible rapping that was interpreted as coded responses of spirits to questions posed by two young sisters, Margaret and Kate Fox. Others soon reproduced the sounds during "spirit circles" or séances around the country. Spiritualists...