In this manner the Kitāb is to be viewed as a classic of early Fāṭimid literature, documenting important aspects of the development of the Ismāʿīlī 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 Shī‘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 Fāṭimid-Isma‘īlī da‘wa throughout the medieval Islamicate world, and the religious and philosophical history of post-Fāṭimid Musta‘lī branch of Ismāʿīlism in Yemen and India.[3]