In elaborating their religious system, the early Ismailis emphasised a fundamental distinction between the exoteric (zahir) and the esoteric (batin) dimensions of the sacred scriptures and the religious commandments and prohibitions. Accordingly, they held that the revealed scriptures, above all the Qur’an, and the laws laid down in them, had their apparent or literal meaning, the zahir, which had to be distinguished from their inner meaning or the true spiritual reality, hidden in the batin. They further held that the zahir, or the religious laws enunciated by the messenger-prophets, underwent periodical changes while the batin, containing the spiritual truths (haqa’iq), remained immutable and eternal.
The hidden truths could be made apparent through ta’wil, esoteric exegesis, the process of educing the batin from the zahir. Similar processes of exegesis or hermeneutics existed in early Judaeo-Christian as well as Gnostic traditions, but the immediate antecedents of Isma‘ili ta’wil, also known as batini ta’wil, may be traced to the Shi‘i milieus of the 2nd/3rd century AH in southern Iraq, the cradle of Shi‘ism.
The Ismailis also taught that in every age, the esoteric world of spiritual reality could be accessible only to the elite (khawass) of mankind, as distinct from the common people (‘awamm) who were merely capable of understanding the zahir, the apparent meaning of the revelations. In the era of Islam, the eternal truths of religion could be revealed only to those who had been properly initiated into the Isma‘ili da‘wa and community and recognised the teaching authority of the Prophet Muhammad’s wasi or legatee, Imam ‘Ali b. Abi Talib, and the imams who succeeded him in the Husaynid ‘Alid line. They alone, collectively designated as the ahl al-ta’wil or ‘people of ta’wil’, represented the sources of knowledge and authoritative teaching (ta‘lim) in the era of Islam. These authorised guides were, in fact, the very same people referred to in the Qur’an (3:7) by the expression al-rasikun fi’l-‘ilm or ‘those possessing firm knowledge’. The centrality of ta’wil for the early Isma‘ilis is attested by the fact that the bulk of their literature is comprised of the ta’wil genre of writing, which seeks justification for Isma‘ili doctrines in Qur’anic verses.
The Isma‘ilis taught that the eternal truths, the haqa’iq, hidden in the batin, represented the true message common to Judaism, Christianity and Islam. However, the truths of these monotheistic Abrahamic religions recognised in the Qur’an had been veiled by different exoteric laws as required by changing circumstances. Fully aware of their ‘ecumenical’ approach, the early Isma‘ilis developed the broader implications of these truths in terms of a gnostic system of thought, a system that represented a distinctly Isma‘ili esoteric worldview. The two main components of this system were a cyclical history of revelation and a cosmological doctrine with its integral soteriology.
By the early 280s AH/890s CE, the Ismailis had already developed a cyclical interpretation of time and the sacred history of mankind, which they applied to the Judaeo-Christian revelations as well as a variety of pre-Islamic religions such as Zoroastrianism, Mazdakism and Manichaeism. They conceived of time as a progression of cycles or eras, dawrs (Arabic plural, adwar), with a beginning and an end. On the basis of their eclectic temporal view, reflecting Greek, Judaeo-Christian and Gnostic influences as well as Shi‘i eschatological ideas, the Ismailis elaborated a view of sacred history in terms of eras of different prophets recognised in the Qur’an. The prophetic interpretation of the religious history of mankind was moreover combined with the Ismaili doctrine of the imamate, which had been inherited from the earlier Imami Shi‘is.
According to their cyclical view, the Ismailis believed from early on that the sacred history of mankind proceeded through seven prophetic eras of various durations, each one inaugurated by a speaker-prophet or enunciator (natiq) of a divinely revealed message which in its exoteric (zahir) aspect contained a religious law (shari‘a). The natiqs of the first six eras of human history were Adam, Noah (Nuh), Abraham (Ibrahim), Moses (Musa), Jesus (‘Isa) and Muhammad, respectively. These natiqs had enunciated the outer (zahir) aspects of each revelation with its rituals, commandments and prohibitions, without explaining details of its inner (batin) meaning. For that purpose, each natiq was succeeded by a legatee (wasi), also called the ‘silent one’ (samit) and later the ‘foundation’ (asas), who revealed to the elite the esoteric truths (haqa’iq) contained in the inner (batin) dimension of that era’s message. The first six wasis of sacred history were Seth (Shith), Shem (Sam), Ishmael (Isma‘il), Aaron (Harun), Simon Peter (Sham‘un al-Safa’) and Imam ‘Ali b. Abi Talib. In every era (dawr), each wasi was, in turn, succeeded by seven imams, also called atimma’ (singular, mutimm, completer), who guarded the true meaning of the divine scriptures and laws in both their zahir and batin aspects. The seventh imam (or mutimm) of every dawr would rise in rank to become the natiq of the following era, abrogating the shari‘a of the previous era and proclaiming a new one. This pattern would change only in the seventh, final dawr of hierohistory.
In the sixth dawr, the era of the Prophet Muhammad and Islam, the seventh imam was Imam Muhammad b. Isma‘il b. Jafar al-Sadiq who, according to the bulk of the early Ismailis, had gone into concealment as the Mahdi. On his reappearance, as the Mahdi or qa’im, the restorer of justice on earth and true Islam, he would become the seventh natiq, initiating the final era. However, unlike the previous speakers, Imam Muhammad b. Isma‘il would not bring a new shari‘a to replace the sacred law of Islam. Instead, as is expected in the final eschatological age, his own mission would consist of fully revealing to all mankind the hitherto hidden esoteric truths (haqa’iq) concealed in all the preceding revelations, the immutable truths of all religions which had previously been accessible only to the elite (khawass) of mankind. In this final, messianic age, there would be no need for religious laws. Imam Muhammad b. Isma‘il would, thus, unite in himself the ranks of natiq and wasi, also being the last of the imams, the eschatological Imam Mahdi. In the final, millenarian age of pure spiritual knowledge, the haqa’iq would be completely freed from all their veils and symbolism. In the messianic era of the Mahdi, there would no longer be any distinction between the zahir and the batin, the letter of the law and its inner spirituality. On his advent, heralding the end of time and human history, Imam Muhammad b. Isma‘il would rule in justice as the eschatological qa’im before the consummation of the physical world. The whole cycle from Adam to the advent of the qa’im as the seventh natiq was also called the ‘era of concealment’ (dawr al-satr), because the spiritual truths (haqa’iq) were then concealed in the laws. By contrast, the seventh era, when the truths would be fully revealed to mankind by the qa’im, was designated as the ‘era of manifestation or unveiling’ (dawr al-kashf).
The Ismaili cyclical view of sacred history was evidently first committed to writing by the da‘is of the Iranian lands, notably Muhammad b. Ahmad al-Nasafi (d. 332 AH/943 CE), whose major work Kitab al-mahsul has not survived, and Abu Hatim (d. 322 AH/934 CE), whose ideas on the subject are mainly expounded in his Kitab al-islah. However, these authors and their early successors, especially Abu Ya‘qub al-Sijistani (d. after 361 AH/971 CE), disagreed on certain details of the seven prophetic eras. Al-Nasafi and al-Razi also devoted much energy and creative thinking to accommodating a number of pre-Islamic religions, notably those of the Zoroastrians, Manichaeans and Sabaeans, within their scheme of the seven revelational eras of sacred history, assigning these religions to specific dawrs and natiqs. Abu Hatim al-Razi also introduced the concept of an ‘interim period’ (dawr al-fatra), marked by the absence of imams and occurring at the end of each prophetic dawr, between the disappearance of the seventh imam of that era and the advent of the natiq of the following era. According to him, the Zoroastrians, for example, belonged to the fourth era, the dawr of Moses, and Zoroaster himself had appeared during the interim period at the end of that dawr. It was in the light of such doctrines, rooted in a syncretic and ecumenical worldview, that the Ismailis began to develop their system of thought, a system that appealed not only to Muslims belonging to different communities of interpretation and social strata but also to adherents of a diversity of non-Islamic religious traditions. Of all the Muslim communities, only the Ismailis accommodated in so comprehensive and overt a fashion, in their cyclical scheme of sacred history, the Judaeo-Christian traditions as well as a variety of other pre-Islamic Iranian religions, which were at the time still enjoying some prominence in Persia and Central Asia.
The cyclical prophetic view of sacred history elaborated by the early Ismailis was retained by the Fatimid Ismailis, who refined or modified certain aspects of it, especially in connection with the duration of the sixth dawr, the era of Islam. In the aftermath of the schism of the year 286 AH/899 CE in the Ismaili movement, the dissident Qarmatis of Bahrayn and elsewhere continued to adhere to the earlier scheme, and awaited the return of Imam Muhammad b. Isma‘il who as the Mahdi and the seventh natiq was expected to end the era of Islam and the validity of its shari‘a. The Qarmatis remained intensely preoccupied with prophesies on the advent of the Mahdi and the circumstances of the seventh dawr, which would supersede the era of Islam. The sacrilegious acts of the Qarmatis of Bahrayn in Mecca in 317 AH/930 CE, when they also dislodged the Black Stone (al-hajar al-aswad) from the corner of the Ka‘ba and then kept it for some twenty years at their new capital al-Ahsa’, should be viewed in this context.
On the other hand, the Fatimid Ismailis, who now upheld continuity in the imamate, allowed for more than one heptad of imams in the era of Islam. For them, the seventh dawr, earlier defined as the spiritual age of the Mahdi, had now completely lost its messianic appeal. The final age, whatever its nature, was henceforth postponed indefinitely into the future; and the functions of the eschatological Mahdi or qa’im, who would initiate the Day of Resurrection (yawm al-qiyama) at the end of time, were similar to those envisaged by other Muslim communities. Meanwhile, Imam Muhammad b. Isma‘il himself was not expected to return as the Mahdi; his functions in its original sense had been taken over by his khulafa’, vicegerents, who eventually ruled as the Fatimid caliph-imams. Furthermore, some da‘i-authors of the Fatimid period introduced new concepts into the cyclical scheme. Nasir-i Khusraw (d. after 462 AH/1070 CE), the chief da‘i in Khurasan, for instance, distinguished between a grand cycle (dawr-i mihin), encompassing the entire sequence of the seven prophetic eras, and a small cycle (dawr-i kihin), coinciding with the latter part of the grand cycle and including the era of Islam and thereafter.
Later Ismailis introduced further innovations into the earlier interpretation of sacred history expressed in terms of seven prophetic dawrs. On the basis of astronomical calculations, the Tayyibi Musta‘lian Isma‘ilis of Yemen, who essentially retained the Fatimid traditions in the doctrinal field and the earlier Ismaili interest in cyclical hierohistory and cosmology, conceived of a grand aeon (kawr a‘zam) comprised of countless cycles, each divided into seven dawrs, which would be consummated in the qa’im of the ‘great resurrection’ (qiyamat al-qiyamat). The grand aeon, estimated to last 360,000 times 360,000 years (or 130 billion years), was held to progress through successive cycles of concealment (satr) and manifestation (kashf or zuhur), each composed of seven dawrs. An unknown number of successive cycles of concealment and manifestation had occurred until the present cycle of satr, which was initiated by the historical Adam of the Qur’an, the first natiq of the present age. When this cycle is closed by the seventh natiq and the expected qa’im of the current cycle, there will begin another cycle of manifestation, inaugurated by a partial Adam (Adam al-juz’i), and so on. The countless alternations of these cycles will continue until the appearance of the final qa’im, proclaiming the final qiyama, the Resurrection of the Resurrections (qiyamat al-qiyamat), at the end of the grand cycle. The consummation of the grand aeon will also mark the end of the Tayyibi Ismaili mythohistory.
The early Nizari Ismailis under the initial leadership of Hasan-i Sabbah (d. 518 AH/1124 CE) established a principality in Persia, with a branch in Syria. The Nizaris, who enjoyed political prominence during the Alamut period of their history (487-654 AH/1094-1256 CE), followed a religious and political path of their own and they, unlike the Tayyibi Ismailis, were not particularly concerned with the earlier cyclical view of religious history, though they generally continued to adhere to the earlier scheme of seven prophetic dawrs. Confronting the enmity of the Saljuq Turks and others, the Nizaris of Persia, who were more preoccupied with their survival, did not produce many learned scholars. Nevertheless they did maintain a sophisticated outlook and elaborated their teachings revolving around the central Shi‘i doctrine of ta‘lim, or authoritative teaching by the imam of the time.
In the year 559 AH/1164 CE, the Nizari imam proclaimed the qiyama or Resurrection symbolically for his community. Thereafter, the implications of this declaration were elaborated in terms of the doctrine of the qiyama that also introduced a further element into the cyclical sacred history in the form of the figure of the imam-qa’im, the imam inaugurating the era of qiyama, also making every Nizari imam potentially a qa’im. In elaborating the doctrine of the qiyama, the Nizaris allowed for transitory eras of resurrection during the dawr of Prophet Muhammad who, like the preceding five natiqs, had initiated an era of concealment (dawr al-satr). In the era of Islam, and in especial honour of Prophet Muhammad’s greatness, there could be occasional partial eras of resurrection, at the discretion of the current Nizari imams, each offering a foretaste of the Great Resurrection that would occur at the end of the sixth era initiated by Prophet Muhammad. The Great Resurrection would inaugurate the final, seventh era in the sacred history of mankind. As noted, the condition of qiyama could in principle be granted at any time by the current Nizari imam, who was potentially also a qa’im. Consequently, in the era of Islam and Prophet Muhammad, life could alternate, at the will of the current imam, between eras of qiyama and satr, the normal condition of human life. And using Ismaili ta’wil, the Nizaris interpreted the qiyama spiritually as the manifestation of the unveiled truths (haqa’iq) in the person of the Nizari imam, while satr meant the concealment of the true spiritual reality of the imam, when truths were again hidden in the batin of the laws, requiring the strict observance of the shari‘a and taqiyya (precautionary dissimulation).
With the destruction of the Nizari Ismaili state in Persia by the Mongol hordes in 654 AH/1256 CE, the Nizaris lost their political prominence. For centuries thereafter they lived in scattered communities, disguising themselves under the covers of Sufism, Sunnism and Twelver Shi‘ism. During the Anjudan revival in Nizari da‘wa and literary activities, lasting some two centuries until around 1100 AH/1688 CE, the Nizaris essentially reiterated the doctrines elaborated during the earlier Alamut period of their history, with only occasional references to cyclical time and sacred history.
 On the earliest of the Ismaili movement, see al-Hasan b. Musa al-Nawbakhti, Firaq al-Shi‘a, ed. H. Ritter (Istanbul, 1931), pp. 57-58, 60-6; Sa‘d b. ‘Abd Allah al-Qummi, Kitab al-maqalat wa l-firaq, ed. M. J. Mashkur (Tehran, 1963), pp. 80-81, 83, and F. Daftary, “The Earliest Isma‘ilis”, Arabica, 38 (1991): 220ff.; reprinted in E. Kohlberg, Shi‘ism (Aldershot, 2003), pp.235ff.
 See F. Daftary, “A Major Schism in the Early Isma‘ili Movement”, Studia Islamica, 77 (1993): 123-139; reprinted in revised form in his Ismailis in Medieval Muslim Societies (London, 2005), pp.45-61
 Ibn Hawshab Mansur al-Yaman, Kitab al-rushd wa l-hidaya, ed. M. Kamil Husayn, in Collectanea, ed. W. Ivanow (Leiden, 1948), pp. 189, 191-192, 197ff.; Ja‘far b. Mansur al-Yaman, Kitab al-kashf; ed. R. Strothmann (London, etc., 1952), pp. 14ff., 50, 97, 103-104, 109, 113-114, 132-133, 138, 150, 169-170; Abu Hatim al-Razi, Kitab al-islah, ed. H. Minuchihr and M. Muhaqqiq (Tehran, 1377/1998), pp. 211-220 and elsewhere; Abu Ya‘qub al-Sijistani, Ithbat al-nubuwwat (al-nubu’at), ed.‘Arif Tamir (Beirut,1966), pp. 181-193; idem, Kitab al-iftikhar, ed. I. K. Poonawala (Beirut, 2000), pp. 123-137, and H. Corbin, Cyclical Time and Ismaili Gnosis (London, 1983), pp. 1-58.
 Abu Hatim al-Razi, 148-167; al-Sijistani, 82-83; Corbin, 187-193; S. M. Stern, Studies in Early Isma‘ilism (Leiden-Jerusalem, 1983), pp. 30-46, and F. Daftary, The Ismailis: Their History and Doctrines (Cambridge, 1990), pp. 234-239.
 See al-Qadi Abu Hanifa al-Nu‘man b. Muhammad, Asas al-ta’wil, ed. ‘Arif (Beirut, 1960), pp. 40-368; S. M. Stern, “Heterodox Isma‘ilism at the Time of al-Mu‘izz”, Bulletin of the School of Oriental and African Studies, 17 (1955): 10-33; reprinted in his Studies, 257-288, and Daftary, The Isma‘ilis, pp. 176-179, 218-220, 234.
 Nasir-i Khusraw, Wajh-i din, ed.G.R. A‘vani (Tehran, 1977), pp. 62-64, 126-127, 169-170, 245, 256,331.
 Those ideas are expounded in the metaphysical system of the Tayyibi da‘is who articulated their gnostic haqa’iq system in numerous treatises. See, for instance, Ibrahim b. al-Husayn al-Hamidi (d. 557 AH/1162 CE), Kitab kanz al-walad, ed. M. Ghalib (Wiesbaden, 1971), pp. 149ff., 205-227, 232ff., 258-272; al-Husayn b. ‘Ali Ibn al-Walid (d.667 AH/1268 CE), Risalat al-mabda’ wa’l-ma‘ad, ed. H. Corbin in his Trilogie Ismaelienne (Tehran-Paris,1961), text pp. 100ff., 121-128, and Corbin, Cyclical Time, 37-58.