Spiritualism is a religious idea that declares that humans can communicate with the dead by making use of ‘mediums’ as part of their services to contact those that have ‘crossed over’. It mostly follows Christian traditions and prayers but with the addition of being able to contact the dead.
It was extremely popular in the Victorian period, especially in the USA and UK, with many spiritualist churches catering for a large congregation. Most historians set the beginnings of spiritualism with the Fox Sisters in New York State in the 1840’s and many of the early promoters were women. Before long, the ideas of the church soon became part of entertainment and commerce, with the prospect of talking to the dead being mixed in with fortune-telling, séances, magic and the like. Many practitioners staged ever more elaborate stunts to attract paying audiences.
Harry Houdini spent much of his later career debunking claimed spiritualists but many scientists and otherwise intelligent people fully accepted the ability some people had to talk to the dead, for example Arthur Conan Doyle and Alfred Russell Wallace.