'Kitab al-kashf' is ascribed to the Ismaili da'i Jafar Ibn Mansur al-Yaman. The content of the treatise reflects ideas pervading the milieu of the 9th and 10th century Ismaili missionaries. Concepts of early Shia, 'ghulat' (extremists), those accused of exaggeration ('ghuluww') in religion, Gnosticism, elements of Neoplatonism etc. are also included. It is noteworthy that such a wide range of motifs is placed here within the framework of Ismaili philosophy and theology.