The "Books of Jeu" are two Gnostic texts, the First Book of Jeu and the Second Book of Jeu, which form a single composite work found in the Bruce Codex. These books are considered handbooks for mystical ascent, teaching the secret knowledge (gnosis) necessary for the soul's journey through the cosmic realms to reach the highest divine source after death. They consist of a post-resurrection dialogue with Jesus, revealing the structure of the heavenly realms and the rituals, "seals," and "ciphers" needed to navigate them.