The Spirits' Book (Le Livre des Esprits in French) is part of the Spiritist Codification, and is regarded as one of the five fundamental works on Spiritism. It was published by the French educator Hippolyte Léon Denizard Rivail, under the pen name of Allan Kardec on April 18, 1857. It was the first book published under the name Allan Kardec and remains his best known.
The book is structured as a collection of questions regarding the origin of spirits, the purpose of life, the order of the universe, good and evil, and the afterlife. Its answers, according to Kardec, were given to him by a group of spirits, including one who identified itself as "The Spirit of Truth", with whom he communicated through several mediums in Spiritist sessions during the 1850s. Kardec, who considered himself an "organizer" rather than an author, grouped the questions and their answers by theme, occasionally including lengthier digressions the spirits had dictated to him on specific subjects, some signed by philosophers such as Augustine of Hippo and Plato and writers including Fénelon.
The basic concepts presented by the book are:
Monotheism (i.e. there is only one God, the Supreme Intelligence and the First Cause of all things)
Creationism (i.e. God created and upholds the natural laws that govern the universe)
The validity of Jesus' ethics and moral teachings
The survival of the soul (spirit) after death (disincarnation)
Reincarnation of the souls (plurality of existences)
The inherent morality of God and His/Her creation
The existence of life all over the Universe (plurality of worlds)
All spirits are destined to reach perfection through the progression of the soul, which advances by gaining experience across multiple lives
The migration of spirits from one world to another (transmigration)
The possibility of manifestation of spirits in the living world by means of mediums
Karma (not actually termed such) as an explanation for apparent injustices
Good works are essential for spiritual enlightenment, not just faith
The Spirits Book is divided into four parts or "books", each one split into several chapters. Chapters are not regularly subdivided into sections — though most have titles marking the beginning of particularly sought subjects.
Book One (First Causes) deals with the origins of the universe and the attributes of God.
Chapter 1 (God) is intended to clarify the true essence of God.