 It was the first and remains the most important spiritist book, because it addresses in first hand all questions developed subsequently by Allan Kardec.The book is structured as a collection of questions regarding the origin of the spirits, the purpose of the life, the order of the universe, evil and good and the afterlife.Its answers, according to Kardec, were given to him by a group of spirits who identified themselves as "The Spirit of Truth", with whom he communicated in several Spiritist sessions during the 1850s.