5. A work, of which the title is not mentioned, in explanation of the sayings of Ḥusayn b. Manṣúr al-Ḥalláj (p. 153). 6. _Kitáb al-bayán li-ahl al-`iyán_, on union with God (p. 259). 7. _Baḥr al-qulúb_ (p. 259). 8. _Al-Ri`áyat li-ḥuqúq Allah_, on the Divine unity (p. 280). 9. A work, of which the title is not mentioned, on faith (p. 286). None of these books has been preserved. The _Kashf al-Maḥjúb_,[9] which belongs to the later years of the author’s life, and, partly at any rate, to the period of his residence in Lahore, was written in reply to certain questions addressed to him by a fellow-townsman, Abú Sa`íd al-Hujwírí. Its object is to set forth a complete system of Ṣúfiism, not to put together a great number of sayings by different Shaykhs, but to discuss and expound the doctrines and practices of the Ṣúfís. The author’s attitude throughout is that of a teacher instructing a pupil. Even the biographical section of the work (pp. 70-175) is largely expository. Before stating his own view the author generally examines the current opinions on the same topic and refutes them if necessary. The discussion of mystical problems and controversies is enlivened by many illustrations drawn from his personal experience. In this respect the _Kashf al-Maḥjúb_ is more interesting than the _Risála_ of Qushayrí, which is so valuable as a collection of sayings, anecdotes, and definitions, but which follows a somewhat formal and academic method on the orthodox lines. No one can read the present work without detecting, behind the scholastic terminology, a truly Persian flavour of philosophical speculation. Footnote 9: Its full title is _Kashf al-maḥjúb li-arbáb al-qulúb_ (Ḥájjí Khalífa, v, 215).