in 971. Works Several of al-Sijistani's works survive, having been copied and studied by the Tayyibi Isma'ili communities of Yemen and India. However, as they are regarded as "highly esoteric and restricted", they have been slow to be studied by modern scholars and published in critical editions. Furthermore, as the historian Paul Walker comments, "[a]s they exist now, it is in some cases difficult to determine the original form of the texts", as many survive only in translations or paraphrased summaries. Some works are only known by title or in fragments, being cited or quoted in other works. Kashf al-mahjub The ('Unveiling of the Concealed'), was the first of al-Sijistani's works to become available to scholars. It only survives in a Persian translation, or even paraphrase, of the Arabic original, produced in the 11th century. It comprises seven chapters, each further divided into seven parts. The aim of the work is to 'unveil' divine knowledge (, ), and deals with the concepts of the Oneness of God (), the stages of creation, the nature of prophethood, and resurrection (). Based on its containing passages supporting the idea of metempsychosis, it likely belongs to the early phase of al-Sijistani's career, before he accepted Fatimid orthodoxy. Excerpts of the work were first published by Mahdi Bayani in 1938 (, Tehran, Shirkat-i Chāp-i Khudkār). The Persian text was published with a French commentary in 1949 by Henry Corbin (Tehran, Institut Franco-Iranien & Paris, A. Maisonneuve). Corbin also published a full French translation in 1988 as (Lagrasse, Verdier). A partial English translation was published by Hermann Landolt (Kashf al-maḥjūb, Unveiling of the Hidden) in S.H. Nasr and M. Aminrazavi (eds.), An Anthology of Philosophy in Persia, Volume II (Oxford, Oxford University Press, 2001). Ithbat al-nubu'at The or ('Proofs of Prophecies'). In its seven sections, al-Sijistani "puts forward a variety of proofs for the necessity of prophecy (), also explaining different prophetic eras". According to Paul Walker, it shows signs of later editing, and all available manuscripts are missing the final two sections. The work was published in Arabic in 1966 by Arif Tamir (Beirut, al-Matba'a al-Kathulikiyya). According to Walker, this edition "contains errors, faulty readings, pages out of order, and extraneous passages". Kitab al-iftikhar The ('The Book of Boasting'), is likely the last of al-Sijistani's works, being written around 971. As its title suggests, it is "strikingly polemical and strikingly defensive and apologetic" work;