In this book, André Luiz analyzes the various aspects of mediumistic communication, praising the efforts of mediums who are faithful to the spiritual mandate they received before they reincarnated, and warning them about the risks of badly practiced exchanges between the two worlds. The book deals with psychophony, somnambulism, possession, clairvoyance, clairaudience, out-of-the-body activity, fascination, psychometry, and physical effects mediumship, among other related subjects. It is a technical study of great relevance that reveals how spirits act in the intricate process of communicating with incarnates. It transmits concepts of highly evolved spirit mentors in expositions of scientific and evangelical content indispensable to those who have dedicated themselves to the study of the subject.