Edgar Cayce was a claimed clairvoyant who though connecting with his "higher self" in a trance like state, spoke of all sorts of subjects both controversial and mundane.  These sessions were often recorded and in them he discussed medical practices, the nature of the afterlife, and interestingly enough... a lot about the Lost City of Atlantis.  Cayce founded the Association for Research and Enlightenment to record the results of his sessions and attempt to put the advice to use, which still exists today.  Much of the modern New Age movement owes its ideas to Cayce's sessions.