The Book of the Sage and Disciple () is a religious narrative of spiritual initiation written in the form of a dramatic dialogue by Ja'far ibn Mansur al-Yaman (270 AH/883 CE – c. 347 AH/958 CE). The work describes the encounter of a disillusioned young man with a dā‘ī, or Isma'ili Muslim missionary, who gradually introduces his new disciple to the inner dimensions of Islam as elaborated by the Shi'a imāms. Isma'ili Muslims are Shi'a Muslims who believe that Isma'il ibn Jafar (b. 100/719) was the true prophetic successor or imam of Ja‘far al-Sādiq (d. 148/765), as opposed to "Twelvers" who believe that Musa al-Kadhim (d. 183/799) was designated imam over his younger brother Ismāʿīl. After the Abbasid Revolution of 750 CE Ismāʿīlīs came to believe that Muhammad ibn Ismail, son of the seventh imam and their awaited mahdi, had entered a state of occultation. In his absence Isma'ilis began widely propagating their faith beyond their base of power in Salamiyah through the institution of the da‘wa, or mission led by a dā‘ī. In addition to presiding over the primary missionary activities of the da‘wa, the dā‘ī was responsible for the education, safety and spiritual health of his community. The personal relationship of the dā‘ī and his students, portrayed so vividly by Ja'far ibn Mansur al-Yaman in his work, would decisively influence the sheikh-murīd bond of later Sufi orders. With the rise of the Fatimid Caliphate in the first quarter of the tenth century CE, the Isma'ilis identified these caliphs with their imams. In this manner the Kitāb is to be viewed as a classic of early Fatimid literature, documenting important aspects of the development of the Isma'ili da‘wa in tenth-century Yemen. The Kitāb is also of considerable historical value for modern scholars of Arabic prose literature as well as those interested in the relationship of esoteric Shi'ism with early Islamic mysticism. Likewise is the Kitāb an important source of information regarding the various movements within tenth-century Shī‘ism leading to the spread of the Fatimid-Isma'ili da‘wa throughout the medieval Islamic world, and the religious and philosophical history of post-Fatimid Musta'li branch of Isma'ilism in Yemen and India. The Author Ja'far ibn Mansur al-Yaman was a high-ranking Isma'ili poet, theologian and court companion active during the reigns of the first four Fatimid caliphs. Born to an accomplished Shi'a family of Kufan origins in Yemen, Ja'far was a son of the famous