The Imam, the Divine Guide, is the central point around which the Shi'ite religion turns. The power of Shi'ism comes from the actions of the Imam. This title is reserved exclusively for the sucessors of the prophets in their mission. The author shows that from the beginning of Shi'ite Islam until the tenth century, the Imam was primarily a master of knowledge with supernatural powers, not a jurist theologian. The Imam is the threshold through which God and the creatures communicate. He is thus a cosmic necessity, the key and the center of the universal economy of the sacred. The author presents Shi'ism as a religion founded on double dimensions where the role of the leader remains constantly central: perpetual initiation into divine secrets and continued confrontation with anti-initiation forces. Without esotericism, exotericism loses its meaning. Early Imamism is an esoteric doctrine. Historically, then, at the beginning of esotericism in Islam, we find an initiatory, mystical, and occultist doctrine. This is the first book to systematically explore the immense literature attributed to the Imams themselves in order to recover the authentic original vision. It restores an essential source of esotericism in the world of Islam.