Wickland believed that some mental illnesses were caused by spirits of the dead who had not moved on to the afterlife and were still trapped in the physical world. He called these spirits "earthbound" and believed that they could influence the thoughts and behavior of living individuals, causing them to experience mental and emotional distress.Throughout the book, Wickland shares numerous case studies of patients he treated who were possessed by earthbound spirits. He describes in detail the methods he used to communicate with these spirits and to help them move on to the afterlife.Wickland's approach to treatment involved using hypnosis to bring the patient into a trance state, allowing the earthbound spirit to communicate through the patient's voice. He would then talk to the spirit and try to persuade it to move on to the afterlife. Once the spirit had moved on, the patient's mental and emotional symptoms would often disappear.While some readers may find Wickland's approach controversial, "Thirty Years Among the Dead" provides a unique and fascinating perspective on the nature of consciousness and the possibility of communication with the afterlife. It also offers a compassionate approach to treating mental illness, emphasizing the importance of understanding the underlying spiritual causes of psychological distress.