Complementary and alternative healing concepts encompass a wide range of practices that share a common ground: the belief that our physical well-being is inextricably linked to an unseen world beyond our physical senses. Our view of that world can be traced to two key thinkers: Emanuel Swedenborg and Franz Anton Mesmer. Who were these men, and what shaped their thought? How did their ideas capture the public imagination? How did they speak to movements as diverse as utopianism, spiritualism, psychic healing, and homeopathy? Historian John S. Haller traces the threads of Swedenborg's and Mesmer's influence through the history of nineteenth-century medicine, illuminating the lasting impact these men have had on concepts of alternative healing.