Mahdism in Twelver Shi’ism inherited many of its elements from previous religious trends. Without necessarily going back to Zoroastrianism, Manichaeism, Judaism, and Christianity, to which generally eschatology, messianism, and the apocalyptic in Islam owe many of their doctrines and elements, one can think of numerous Shi’ite and non-Shi’ite sects that existed prior to the definitive transition from earlier Imamism to Twelver Shi’ism in the first half of the 10th century.

According to the traditional date most often retained, Imam Ḥasan Askari, the eleventh Imam, died in 874. His death, like that of previous Imams, gave rise to a period of turbulence among the faithful, but this time the crisis seemed even more serious and the Imamis did not themselves hesitate to call the decades that were to follow “the period of perplexity” or “confusion”. The mysterious fate of the presumed son of the eleventh Imam led to several schisms with notable doctrinal variances. Some groups claimed that his son died at a very young age, others that he had lived until a certain age and then died, and still others simply denied his very existence, believing that Ḥasan Askari never had a son. Only a small minority supported the idea that the son of the eleventh imam was alive, that he was in “occultation,” and that he was to reappear as mahdi  at “the end of time”. This idea was gradually adopted by all Imamis, who thus became known as “Twelvers”.

Sources from this period, reflect, in their particular manner, the hesitation and crisis believers experienced. A close study of these sources indeed seems to show that profound uncertainties and serious lacunae existed regarding a substantial number of important doctrinal elements that became articles of faith. First, the definitive number of Imams and even the notion of “occultation: Abu Jafar Barqi (d. 887 or 893), in his Ketāb al-maḥāsen, contributes no information regarding these two points. In the first chapter, dedicated to different interpretations of numbers, he takes into account the numbers 3 to 10, but says nothing about the number 12. A few decades later, Ebn Bābuya (Ebn Bābawayh, 923-91), known as Shaikh Ṣaduq, in his Ketāb al-ḵeṣāl, reported many traditions regarding the number 12, some among them about twelve. Barqi’s contemporary, Ṣaffār Qomi (d. 902-3) in his Baṣāer al-darajāt mentions only five traditions from a total of almost 2,000 regarding the notion that the Imams were to be twelve in number, and he reports nothing about the occultation. The oldest text of certain authenticity that we have, in which a complete list of the twelve Imams is found, seems to be the Tafsir by Ali b. Ebrāhim Qomi (d. ca. 919; Qomi), a work written some years after what would finally be termed the “Minor Occultation”.

It is only from Kolayni’s (d. 940-41) hadith collection onwards that traditions regarding the definitive number of Imams, and the occultation of the twelfth Imam became more frequent. Even so, a study of chains of transmission (esnād) of these traditions, not only in Kolayni, but also in the two voluminous monographs by his famous successors, namely Ketāb al-ḡayba by Ebn Abi Zaynab Nomāni (d. ca. 956 or 971), and Kamāl al-din by Ebn Bābuya, reveal that elements of older books on the ḡayba belonging to other Shi’ite trends had been appropriated in the service of the cause, and were adapted to Twelver Shi’ite doctrines.

One also encounters signs of hesitation and grasping for ideas concerning the nature and modalities of the occultation. Different theories appear to have co-existed in the decades following the death of the eleventh Imam. One discerns a trace of this in reports regarding a character as influential as Abu Sahl Nowbaḵti (d. 923), who would have played a determining role in the establishment of a definitive form of the theology of occultation. Indeed, the sources attribute two different conceptions of the occultation to him. According to the first, cited by Ebn Bābuya, based on Ketāb al-tanbih wa’l-emāma, a work by Abu Sahl now apparently lost, the Hidden Imam “exists in the world by his spiritual substance thanks to a subsisting essence”. According to a second theory reported by Ebn Nadim (d. 990; in AL-FEHREST), Abu Sahl is said to have maintained that the twelfth Imam died, but secretly left behind a son as a successor to him; the lineage of Imams would thus be perpetuated in occultation from father to son until the final Imam manifests himself publicly as the Mahdi.
Eventually, none of the theories were sustained, but here one recognizes tentative efforts (undoubtedly among the oldest) to rationalize the concept of occultation. During the same period, Abu Jafar Ebn Qebba (d. before 931) wrote some texts with the same objective. The rationalizing theorization of the concept of occultation continued in full force with Shaikh Mofid (d. 1022) and his disciples, Šarif Mortażā (d. 1044), Mo-ḥammad b. Ali Karājaki (d. 1057), and Shaikh Abu Jafar Ṭusi, known as Šayḵ al-Ṭāefa (d. 1067), thinkers who explicitly had recourse to dialectical demonstration drawing notably from some older Mutazilite.

During this period the Imami community underwent what one might consider a serious identity crisis. This “time of confusion” is one of groping in the dark, of research, development, and the more or less painful establishment of doctrines related to the authority and legitimacy of the twelfth Imam. These doctrines were faced with, and overcame, much resistance before eventually standing as articles of faith. The transition from Imami Shi’ism to Twelver Shi’ism was certainly not achieved seamlessly. In the introduction of his Ketāb al-Ḡayba, Ebn Abi Zaynab Nomāni laments the fact that a large majority of his co-religionists still did not know the identity of the Hidden Imam, or even go so far as to contest his existence. Ebn Bābuya makes a similar observation when he says that he was inundated by questions from the Shi’ites of Khorasan regarding the identity of the Hidden Imam and this, in fact, was what prompted him to write his Kamāl al-din.
The main preoccupation of Twelver Shi’ite thinkers at this time was to demonstrate the actual existence of the son of Imam Ḥasan al-Askari, and to establish his legitimate authority as the Hidden Imam. This objective was attained thanks to the sustained efforts of a certain number of thinkers and transmitters of traditions, some of whom have already been cited: Nowbaḵti, Abu Jafar Ebn Qebba, Kolayni, Nomāni, and especially Ebn Bābuya and his masterly Kamāl al-din, the principal architect of the canonization of elements relating to the Hidden Imam, his occultation, and status as eschatological Savior.
Consequently, when Shaikh Ṭusi (d. 1067) wrote his Ketāb al-Ḡayba, a substantial monograph on the subject, articles of faith regarding the Mahdi of the Twelver Imamis appeared already well established: that the son of the eleventh Imam is indeed the twelfth and final Imam; that he had two occultations: during the first and much shorter one, he communicated with believers through the intermediary of four delegates. During the second, which is to last until the end of time, he remains providentially living in his physical body in order to return to save the world as Mahdi. We shall now examine these points in greater detail.

Birth and occultation of the Mahdi

What precisely do traditional accounts of the Mahdi relate? Versions that would eventually be considered “orthodox” began to emerge in the first half of the 10th century and only attained their definitive form in the following century. The eschatological Savior of Imamism is presented as Abu’l-Qāsem Moḥammad b. Ḥasan al-Askari, twelfth and last among the Imams. He therefore bears the same name and konya as the Prophet, thus fulfilling the hadith that probably goes back to Āṣem b. Bahdala (d. 744-45) from Kufa. It undoubtedly owes its origin to Moḵtār’s rebellion in favor of Moḥammad b. al-Ḥanafiya, son of ʿAli, who, once when he was described as Mahdi, declared that his privilege consisted in bearing the same name and konya as the Prophet.

However, according to Kolayni and others it was inadvisable to call the Mahdi by his name, to protect the Savior from the threat posed by the Abbasid court. He was called by any one of his surnames: mahdi (the Guided One), montaẓar (the Awaited One), ṣāḥeb al-zamān (Lord of the Time), al-ḡāeb (the Occulted/Hidden One), ḥojjat Allāh (Proof of God), ṣāḥeb al-amr (Lord of the Cause), baqiyat Allāh (Remainder of God) and, most often, qāem (a complex term meaning among other things: the standing, one who stands up, one who rises, the resurrector). The latter title, which among the Imamis gradually replaced that of Mahdi, was employed in Shi’ite circles to designate the Imam who “stood up” to fight against unjust and illegitimate power.

According to some accounts, his mother, to whom various names are given (Narjis, Rayḥāna, Sawsan, Maryam), was a black slave of Nubian origin (the first three names, being those of flowers and plants, and often given to female slaves, seems to confirm this version); according to other accounts, undoubtedly legendary and hagiographic, she was the grand-daughter of the Byzantine emperor, himself a disciple of the Apostle Simon. According to this version, the Byzantine princess was captured by Muslim troops and sold as a slave in Baghdad to a man belonging to the entourage of the tenth Imam, Ali al-Naqi who then came to Sāmarrā and offered the girl to Ḥakima, the latter’s sister. Even before her captivity, the princess had a dream vision of Mary, mother of Jesus, as well as of Fāṭema, daughter of the Prophet Moḥammad, both of whom had asked her to convert to Islam and let herself be captured by the Muslim armies as she was destined for a glorious life. In Sāmarrā, the tenth Imam, having by clairvoyance recognized in her the future mother of the Mahdi, gave her in marriage to his son Ḥasan, the future eleventh Imam. Signs of the mother’s pregnancy as well as the birth of the child were miraculously concealed, since the Abbasids sought to eliminate an expected child whom persistent rumors described as a Savior. The date most often cited for his birth is 15 Šabān 256/18th July 870 (one of the most important Imami festivals). The father showed the newborn to some forty intimate disciples, and then the child was hidden. According to many accounts, the eleventh imam is said to have adopted a two-fold tactic to guarantee the child’s security. First, apart from his intimate circle, the Imam kept the birth of the child secret, going so far as to designate his mother, Ḥodayṯ, as his sole heir. Now, it is known that according to Imami law, under some conditions the inheritance belongs to the mother of the deceased when the latter does not leave behind a child. Secondly, Imam Ḥasan al-Askari had recourse to a ruse to cloud the issue and distract attention. Some time before his death in 874, he allowed a rumor to spread that his servant Ṣaqil was pregnant with his child. Informants of the caliph al-Motamed (r. 870-92) closely observed the activities of the Imam, who was kept under surveillance in the military camp at Sāmarrā. When, following a serious illness, the Imam’s death seemed inevitable, the caliph dispatched his trusted men to the site. After the eleventh Imam died, his servant was arrested for observation. During the year that followed, she showed no signs of pregnancy and was released and promptly forgotten. The caliph and his entourage were then convinced that the deceased eleventh Imam left behind no descendants. According to Imami authors, divine providence had been accomplished. The twelfth Imam, the awaited Savior, was thus saved and grew up in. This “gilded legend” meets the obvious hagiographic requirements, but at the same time it reflects the uncertainties that continued to be felt in Imami circles regarding the very existence of a child of Imam Ḥasan al-Askari. This led, as we have seen, to a number of schisms. It is certainly no accident that the sources present “the concealed birth” as one of the distinctive signs of the Savior.