History.com: 8 Famous Figures Who Believed in Communicating With the Dead

Spiritualism's popularity waxed and waned throughout the 19th century and the first decades of the 20th century, and surged on the heels of major wars and pandemics. While belief in an afterlife is a cornerstone of many ancient and modern religions and cultures worldwide, the idea that it's possible to communicate with the dead never reached the same level of acceptance. But, for a period of about a century, beginning in the 1840s, sending messages between the human and spirit worlds was popular not only as a religion, but also as a pastime.