The writings of Nasir al-Din al-Tusi illustrate the high level of intellectual life at the Nizari Ismaili fortress of Alamut

Muhammad ibn Muhammad ibn al-Hasan al-Tusi, better known as Nasir al-Din Tusi, one of the major intellectual scholars of the thirteenth century who contributed to many fields of learning, was born on 18 February 1201 in Tus, northeastern Persia, into a Twelver Shi’i (Ithna’ashari) family. His father, a jurist, encouraged al-Tusi to study a range of intellectual disciplines.

In his autobiographical work Sayr wa suluk (‘Contemplation and Action‘), al-Tusi “gives a brief account of his intellectual growth. After mastering all the sciences of his day, from theology and philosophy to mathematics and astronomy, Tusi remained dissatisfied, feeling that he was no nearer the truth [that he had been searching for] than before. What frustrated him more than anything else was the great diversity of opinions he encountered on the most basic issues of life and faith. But there was one school of thought that he had not yet explored, and that belonged to the Ismailis.” (Willey, Eagles Nest p 67-68).

Image: The Institute of Ismaili Studies

Continuing to ponder further, al-Tusi gradually realised that “since mankind is divided in its great diversity of opinions, the attainment of the truth is not possible through intellect and reason alone but required the additional intervention of a mukammil, an agent of perfection, an authoritative instructor or preceptor who is aware of such knowledge in its very essence.” He began to inquire “into the main propagators of this doctrine, the Ismailis … ” (Badakhchani, Contemplation and Action p 3).

Then he chanced to come across some sermons of Imam Hasan II [ala dhikrihi’l-salam [d. 1166]. This discovery had such an impact on Tusi that around 1224 he converted to Ismailism” (Willey, Eagles Nest p 67-68). He communicated his inquiries to the Ismaili governor of Quhistan, Shihab al-Din, and later met him briefly… ” (Willey, Eagles Nest p 67-68).

Shortly thereafter, al-Tusi joined the service of the new Ismaili governor of Quhistan, Naser al-Din Mohtasham, as a resident scholar at the fortress of Qa’in, one of the several strongholds acquired by the Nizari Ismailis of Alamut.

Fortress of Qa’in. Image: Peter Willey, Eagle’s Nest

Nizari Ismaili State of Alamut
In 1090, Hasan Sabbah acquired the fortress of Alamut in northern Iran, marking the founding of what was to become the seat of the Nizari Ismaili state. Over the next 150 years, the Ismailis acquired more than 200 fortresses in Iran and Syria, located in the inaccessible mountainous regions for refuge of the Nizari Ismailis fleeing persecution by the Saljuqs and other rulers during the early Middle Ages. These settlements were also a sanctuary for other refugees, irrespective of their creed, fleeing persecution.

li Castles in Iran and Syria. Image via IIS
Ismaili fortresses in Iran and Syria. Image: The Institute of Ismaili Studies

The Nizari Ismailis of the Alamut period placed a high value on intellectual activities despite having to defend against military attacks. Alamut and several of the Nizari strongholds became flourishing centres of intellectual activities with major libraries containing not only a significant collection of books and documents but also scientific tracts and equipment. The Ismailis extended their patronage of learning to everyone.

The back of the fortress of Alamut which provided the only entrance to the castle. Hasan Sabbah constructed huge underground storage chambers to keep the garrison in food water during times of siege. The Institute of Ismaili Studies

The ruins of the fortresses, especially their water supply systems, are evidence of the ingenious methods adopted by the Persian Nizaris for coping with highly difficult living conditions. Although much of the literature produced by the Nizaris during this time was destroyed by the Mongols, the accounts of some later Persian historians provide information about the community during this period; only a few non-literary items such as coins minted at Alamut have survived.

Archaeological excavations at some of the sites of the castles of Alamut state discovered a variety of kilns, some of which contained fragments of decorated dishes, water-pots, and oil lamps, among other items revealing the artistic skills of the Nizari Ismailis. However, much of the evidence has been removed as a result of land cultivation for agriculture.

Agate beads and fine moulded wares from Andej. Photo: Eagle's Nest
Agate beads and fine moulded wares from Andej, Image: Eagle’s Nest

Al-Tusi at Qa’in
The governor of Qa’in was himself highly learned and encouraged Tusi in his philosophical and scientific researches. “Among the several works Tusi produced here, the most famous is Akhlaq-e Naseri (‘The Nasirean Ethics‘), a masterly synthesis of Neoplatonic and Islamic philosophy.

After ten years of scholarship at Qa’in, Tusi was invited to go to Alamut, the centre of the Ismaili da’wa and intellectual activities. He could now avail himself freely of the rich resources of the Alamut library and also work with other scholars under the patronage of Imam Ala al-Din Mohammad [r. 1221-1255].

A Manuscript of Akhlaq-i Nasiri created for Nasir al-Din Abd al-Rahim, Lahore, Pakistan, ca. 1590-1595. Aga Khan Museum

The next twenty years were the most productive of Tusi’s life, during which time he produced a large number of books on philosophy, mathematics, astronomy, and the applied sciences…. In addition to his scientific works, Tusi composed a number of specifically Ismaili works, including Rawda-yi taslim (‘Paradise of Submission‘), a comprehensive philosophical exposition of Ismaili doctrines…” (Eagle’s Nest p 66-67). It is mainly through al-Tusi’s writings that modern scholars have come to have a better understanding of the Ismaili teachings of the Alamut period” (Daftary, The Ismaili Imams p 141).

The greatest expression of divine mercy to mankind is the appearance of the Imam of the Age
Image: The Institute of Ismaili Studies

Peter Willey notes that the works of Tusi “well illustrate the significance of Ismaili intellectual and cultural life in the early decades of the 13th century, and the role of Alamut in encouraging the advancement of knowledge. As Marshall Hodgson describes it:
“…what was most distinctive was the high level of intellectual life. The prominent early Ismailis were commonly known as scholars, often as astronomers, and at least some later Ismailis continued the tradition. In Alamut, in Khusistan [Quhistan], and in Syria, at the main centres at least were libraries… which were well known among Sunni scholar… the Ismailis prized sophisticated interpretations of their own doctrines, and were also interested in every kind of knowledge which the age could offer” (Eagles Nest p 67-68).

Sources agree that during his long association with the Ismailis, Tusi wrote a number of Ismaili treatises that have either not survived or their Ismaili orientation may have been altered by later scholars or scribes to adapt them to the Twelver Shi’i milieu. “An example of such an amended text is Risala-yi jabr wa qadar (Treatise on Free Will and Predestination), a philosophical work in which quotations from the Fusul-i muqqadas of Imam Hasan Ala Dhikrihi al-Salam have been removed.” In his work Al-Dustur wa da’wat al-mu’minin li al-hudur (Notebook for Summoning the Faithful to the Present Imam) “al-Tusi describes the Ismaili faith as ‘the religion of the theosophers and those travelling in the path of the scholars of divinity, who are followers of the House of Prophethood’” (Badakhchani, Contemplation and Action p 16).

Post Alamut
After the Mongol conquest of Alamut in 1256, Tusi served as the scientific adviser to the Mongol leader Hulegu, who financially supported the construction of the most advanced observatory at Maragha (in present day Azerbaijan).  Tusi worked at the observatory, producing the most influential works in astronomy and mathematics, as well as Ithna’ashari theology, indicating his return to Ithna’ashari Shi’ism (The Ismailis An Illustrated History p 147).

 Stamp issued in the republic of Azerbaijan in 2009 honoring Tusi. Image: Kh. Mirzoyev/Wikipedia

Al-Tusi made monumental contributions to mathematics, establishing trigonometry as an independent subject. He also created the most accurate tables to calculate planetary movements to determine the position of stars and planets and referenced until Copernicus developed one 250 years later. A lunar crater is named after al-Tusi in recognition of his contribution in the field of astronomy.

Stamps honouring Al-Tusi. Image: Alchetron

Nasir al-Din al-Tusi died in Baghdad in 1274. “He left an enduring intellectual legacy for Ismaili and Ithna’ashari Shi’ism as well as for all scholars of ethics, logic, mathematics, metaphysics, and theology” (The Ismailis An Illustrated History p 147).

Islamic Educational, Scientific, and Cultural Organization (ICESCO) List
The site of the fortress of Alamut and four Iranian monuments are registered on the ICESCO’s Islamic World Heritage List (February 2022). More at Tehran Times.

Further reading: Fabricated Medieval Tales

Aziz Merchant, Nasir al-Din al-Tusi and Astronomy, The Institute of Ismaili Studies
Farhad Daftary, Zulfikar Hirji, The Ismailis An Illustrated History, Azimuth Editions
Farhad Daftary, The Ismaili Imams, I.B. Tauris, London, 2009
Jalal Badakhchani, Paradise of SubmissionSynopsis, The Institute of Ismaili Studies
Peter Willey, Eagle’s Nest: Ismaili Castles in Iran and Syria, I.B. Tauris, London, 2005
Rosalind A. Wade Haddon “Ismaili Pottery from the Alamut Period,” published in Eagle’s Nest, Ismaili Castles in Iran and Syria, Peter Willey, I.B. Tauris Publishers, London, 2005
Nasir al-Din al-Tusi, Encyclopaedia Britannica

Contributed to Ismailimail by Nimira Dewji. Nimira is an invited writer although she has contributed several articles in the past (view previous articles). She also has her own blog – Nimirasblog – where she writes short articles on Ismaili history and Muslim civilisations. When not researching and writing, Nimira volunteers at a shelter for the unhoused, and at a women’s shelter. She can be reached at

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