Allan Kardec's supreme handbook about the world of the spirits and the movement of Spiritism is a valuable and insightful guide to existences beyond our corporeal realm. Kardec begins this work by delving into the historical significance of spirits, their connection with God and the physical universe. How spirits are situated in the world, and how they move unseen between the planes of existence, is discussed. The second part concentrates on The Spirit World in greater detail. The types of spirits and how they are incarnated are detailed, with Kardec proposing that several distinct planes of existence are extant, and that most individuals proceed through life without knowing or seeing their influence. A chapter is devoted to how spirits might intervene in our everyday, corporeal world. Often these excursions have a purpose; the spirits are on a mission to inform someone, or change something, that harmony may be restored.