The book explores the concept of telepathy, which is the supposed ability to communicate information from one mind to another without using any known physical channels or senses.In the book, Grumbine presents various theories and experiments related to telepathy. He discusses the history of the concept, different types of telepathy, and the role of the unconscious mind in telepathic communication. He also explores the connection between telepathy and other phenomena, such as hypnosis and clairvoyance.While the book was popular in its time, it is important to note that the scientific community does not generally recognize the existence of telepathy as a valid phenomenon. Many of the experiments and claims presented in the book have been criticized and debunked by modern scientists.Overall, "Telepathy, Or, The Science of Thought Transference" remains an interesting historical document on the topic of telepathy and the early scientific exploration of psychic phenomena.