Nasir al-Din Tusi and His Socio-Political Role in the Thirteenth Century
By: Abbas Ali Shameli
In the history of human civilization as a whole and in that of Islamic civilization in particular, there have been outstanding figures who played decisive roles in forming or changing various aspects of human life. Some of them are still surrounded by a mass of historical data containing contradictory judgments about them. Since their activities took place many centuries ago, modern scholars are often short of enough information to judge their real impact.
It is difficult to come to a fair conclusion. In the history of Islamic civilization, Khāja Nasir al-Din Tusi (597-1201/672-1274) was a unique scholar, in one of the most crucial periods, whose real role and personality are still obscure. His age was full of such harsh socio-political events in all parts of the Islamic world that some regarded it as the worst period in human history.
The intercontinental Mongol invasion and the collapse of all Islamic powers and states at the same time as the abolishment of Ismāʻili fortresses and the destruction of the Abbasid caliphate created a bloody and unstable condition for all Muslims including Tusi. In this complicated atmosphere, one can hardly rely on historical data which are conflicting and controversial.
Considering these difficulties, this paper attempts to assess Tusiís role as a person who witnessed the situation but stood apart from it, preventing himself from assimilating to his age. Holding the chain of Islamic thought, Tusi played an active role in linking pre-Mongol civilization to the post-Mongol world.
Trying to obtain a better and wider understanding of Islamic knowledge, Tusi left Nishāpur, visited Ray, Baghdād and Musil. He witnessed the socio-political situation of the Abbasid caliphate and evaluated the possibilities of being influential in Baghdād.
On his way home, he visited an Ismāʻili leader (dāʻi) in Isfahān, spent a few months in one of their fortresses, and finally joined their central forts in Quhistān and Alamut. He then accompanied Hulākū, took over the administration of Awqāf (endowments), and concentrated his efforts in establishing the observatory of Marāgha.
It is difficult to decide what Tusiís real ideas were and which cause he truly supported. His letter to Ibn al-ʻAlqami the Shiʻi vizier of al-Mustaʻsim, requesting a position that would bring him into contact with the caliph, his long lasting connection with the Ismāʻili elite and his supervision of the institute of Awqāf to administer the observatory of Marāgha are some aspects which will be dealt with in this paper.
In addition to his significant intellectual influence, did Tusi play an active socio-political role or did he manifest a kind of withdrawal and negative cooperation? A discussion of this question will form the core of this paper.
Abu Jaʻfar Muhammad b. Muhammad b. Hasan b. Abi Bakr (Khāja Nasir al-Din Tusi) was born into a learned family known as Firuz Shāh Jahrudi, the name of one of his ancestors. Jahrud was a city in Sāva, originally a province in Iran, which later became a suburb of Qum. Since he was born in Tus on 11th Jumādā I 597 (Feb. 18, 1201), he is known as Tusi.
He died in Baghdād on the 18th Dhu al-Hijjah 672 (June 26, 1274).  As Islamic history indicates, Tusi was one of the most distinguished figures produced by Islamic civilization. Nonetheless, one can hardly form a clear picture regarding his true personality and influence from historical data. Shiʻi and Sunni scholars offered divergent points of view concerning his socio-political impact and his beliefs.
According to G. Sarton, Tusi was one of the greatest scientists of Islam.  Ibn Khaldun similarly believes that most Muslim scholars were from Iran, asserting that there were not any important scholars after Ibn al-Khatib Fakhr al-Din al-Rāzi (544-606 A.H.) and Nasir al-Din Tusi. 
Imāmi scholars (Twelver Shiʻi scholars) like Muhaqqiq al-Hilli (d. 676) in his introduction on R. Istishbāb Tayāsur al-Qiblah li Ahl al-ʻIrāq  and Husayn b. ʻAbd al-Samad in his permission (ijāzah) to Sayyid Badr al-Din Hasan b. Shadqam considered Tusi to be the greatest Imāmi scholar.  He is also entitled ďustād al-bashar wa al-ʻaql al-hādi ʻasharĒ (the Teacher of humanity and the 11th Intelelct). 
Most Sunni scholars, however, such as Abi al-Fallāh Hanbali, Subki, Yāfiʻi, Ibn Taymiyya and Ibn al-Qayyim, accused him of treachery and infidelity. However, Salāh al-Din Safadi  and Ibn Shākir al-Kutubi,  also Sunni scholars, considered him to be a wise and true Muslim.  Tusiís unique significance was due to his wide and profound knowledge on almost all aspects of Islamic learning, including Islamic philosophy, logic, jurisprudence, theology, mysticism, ethics, medicine, astrology and mathematics.
Tusiís Socio-political role
In the first period of his life, Tusi migrated from Tus to Nishāpur where he spent several years. We do not know much about his career as a student. We are also short of accurate information about a sudden circle which Tusi formed by traveling from Nishāpur to Ray, Baghdād, Musil, Isfahān, and again to Nishāpur. The second phase of Tusiís life can be divided into four main periods.
The first and the second parts were spent among the Ismāʻilis. After he had spent several years with Nāsir al-Din Muhtasham (d. 655), the ruler of Quhistān, he was invited to Alamut by ʻAlāí al-Din Muhammad (d. 653) the major leader of the Ismaʻilis.
He stayed for several years in Alamut and witnessed ʻAlāí al-Dinís reign and one year of the reign of his son Khurshāh (d. 654). Historical sources do not indicate whether Tusi played any major socio-political role among the Ismāʻilis other than his intellectual activities.
Some historical accounts show that the only significant political action of the scholar in this period is a letter and an elegy or qasida, to Ibn al-ʻAlqami (d. 656/1258). As a Shiʻi chief minister of the caliph of Baghdād al-Mustaʻsim (from 1245-1258), al-ʻAlqami was in a position to present the caliph with Tusiís letter, in which the scholar praised the caliph, wishing to acquire his favor toward the Imāmi sect. 
Clearly, in the beginning, Tusi felt a responsibility to spread Shiʻi thought. Under the benefit of the patronage of Ibn al-ʻAlqami, he started his missionary activity with the caliph of Baghdād.
From 654 A.H., when the fortresses of the Ismāʻilis collapsed, Tusi started the third and fourth periods of his life, during which he not only accompanied the Mongols to Baghdād but also remained with them until the end of his life.  In the final period of his life, he was appointed supervisor of endowments (Awqāf) and chief of the scholars. In this period he managed to established the observatory at Marāgha. 
Tusi and the Shiíi Seveners (Ismailis)
Tusi began his career as an astronomer for the Ismāʻili ruler Nāsir al-Din ʻAbd al-Rahim in Sertakht.  He spent over 25 years among the Nazāri Ismʻilis. This Shiʻi group was alternatively known as Esoterists, Hermanutists (Bātiniyyah wa ahl al-Taíwil) or Seveners.
At the same time they were known as Infidels (Malāhida) by more orthodox Muslims. From Hasan Sabbāh, the founder of the Nazāri IsmāĎiliís, they took two names: SabbaĎiyya, as an indication of their allegiance and Taʻlimiyya because they followed his instructions: ďin addition to reasoning and thinking, people need a teacher and a guide to teach them how to know God.Ē They were also known by the names of their more influential leaders; for example, they were called QarāmiTa after Ahmad Ibn Ashʻath QarmaTi one of their dāʻi in the second half of the 3rd century and Maymuniyya after ʻAbd Allah Ibn Maymun al-Qaddāh an Ismāʻili supporter between 204-264 A.H.. Their opponents superstitiously called them Hashishiyya from the belief that they used drugs to entice their followers into obeying their orders.  Finally, they are known in the west as Assassins.
Why did Tusi, undoubtedly an Imāmi scholar, join the Shiʻi Seveners, and what was the real reason for his connection with the Ismāʻilis? It is difficult to find the real reason or the exact time in which Tusi joined the Seveners. Some believe that Tusi was, in fact, an Ismāʻili Shiʻi who was born into an Ismāʻili family. However, we should note that his father, Muhammad Ibn Hasan, was one of the zāhiri Shiʻi scholars of Tus. We lack any information which indicates that his family had any kind of relationship with the Ismāʻilis.
Tusi himself in his R. Sayr va Suluk states that he had been trained among a family who believed in and acted according to the zāhir of Shariʻa.  Was he really an Ismāʻili Shiʻa? If not, how can we justify those part of his writings which were written to support the Seveners or at least dedicated to the Ismāʻili leaders?
An answer to this question requires a comprehensive look at the roots of his connection to the Seveners. Some scholars held the idea that as a truth-seeking scholar, Tusi wanted to obtain a real picture of the Seveners, not through the assertions of their opponents, but by studying their literature and by discussions with their scholars.
Accordingly, he decided to live among them.  This idea is defended by the fact that Tusiís involvement occurred after he had observed a considerable change in Ismāʻili ideas. When he was eleven years old, the Seveners in Iran and Syria returned to the appearance (zāhir) of Islam. 
According to Ibn al-Athir, in 608 Jalāl al-Din Hasan send a person to Baghdād announcing to al-Nāsir li Din Allah, the Abbasid caliph, that the Seveners had returned to the Shariʻa and conduct acceptable to all Muslims. When Jalāl al-Dinís mother entered Baghdād on her way to the hajj, she was greatly honored by the Abbasid caliph.  This change might have facilitated Tusiís later relations with the Ismāʻilis since they were no longer rejecting the appearance of the Shariʻa.
Some historians believe that Tusiís connection with the Seveners was the result of the socio-political atmosphere of the time. The Mongolsí continuous invasions in the northern part of Iran, on one hand, and the rigidity of the Sunnis, who formed the majority of the population, on the other hand, forced Tusi to look for a secure and suitable place for his research.
According to the introduction of Akhlāq-i Nāsiri, after the Mongol invasions of Khurāsān and Nishāpur, he left his hometown to go to Ray, then to Baghdād and Musil. Finally, on his way home, he visited Isfahāan and then returned to Khurāsān.  However, his return was unfortunate because he found himself at the center of the war which had covered all the northern parts of Iran.
The Mongol invasions had created a situation of insecurity and massacre. Hence, when he was invited to Quhastān by the Ismāʻili leader Nāsir al-Din Muhtasham, he accepted the invitation.  However, according to Tusiís statement at the end of his commentaries on Ibn Sināís K. al-Ishārāt wa al-Tanbihāt, fleeing to the Seveners did not ease his difficulties; rather, it was the hardest and most difficult period of his life.
Although he received honour and appreciation from them, he could not tolerate many of their ideas and actions. The first evidence of his dissatisfaction among the Seveners is that during his early stay in Quhistān, he communicated with Ibn al-ʻAlqami in an attempt to find a position in Baghdād. 
Tusiís intentions became clear to the rulers of the Ismāʻili forts and they sent him to Alamut where they kept him in a more controlled situation among themselves until the fall of their dominance.  In his introduction of Zij-i Ilkhāni, Tusi praises Hulāku, describing him as the person who freed him from the infidels. Another piece of evidence of Tusiís disagreement with the Assassins is that, soon after he was out of Alamut, he changed the introduction and afterword of Akhlāq-i Nāsiri, which had praised Nāsir al-Din Muhtasham and ʻAlāí al-Din Muhammad Ibn Jalāl al-Din, two Ismāʻili leaders. 
J. Humāíi states that a comparison between the first version and the revised version of Akhlāq-i Nāsiri shows that after Tusi was accused of being a Sevener, he omitted the first and the last parts of Akhlāq-i Nāsiri and modified those parts of his writings which were compatible with their ideas and were written when he was living among them. 
In addition, prior to his death in Baghdād he requested that his body be buried in front of the shrine of Musā al-Kāzim, the other son of Jaʻfar al-Sādiq and the seventh Imām of Twelvers,  rather than the tomb of Ismāʻil, the first hidden Imām of the Seveners.
M. Zanjāni quotes the author of Durrat al-Akhbār who believed that Tusi was forced to live among the Seveners. He states that Tusi was captured and was sent first to Quhistān and then to Alamut.  It is fairly reasonable to conclude that during the period of Tusiís life among the Seveners, he practiced taqiyyah.
Tusi and the fall of the Abbasid caliphate
A quick glance at Tusiís life reveals that he was simultaneously dissatisfied with the Seveners and their ideas and with the Abbasid caliphs. After Hulāku conquered Alamut in 654 A.H., Tusi accompanied him to Baghdād. According to Rashid al-Din Fazl Allah, Manqu Qāíān, the great khān of Qarā Qurm, ordered Hulāku to force Tusi into his army.
Manqu Qāíān, familiar with astrology and mathematics, was interested in establishing an observatory in his territory. Aware of Tusiís expertise in this field, he asked Hulāku to send the scholar to his court after he had conquered the Ismāʻili fortresses. 
In discussing Tusiís reasons for traveling with Hulākuís court, Hāíiri notes that the Mongol kings were extremely interested in history and astronomy. They saw these as the main instruments of their expansion: history to record their expeditions and astrology to predict their chances of success in a new attack. He concludes that they invited Tusi to accompany them as a renowned astrologer. 
According to some historical documents, Tusi not only encouraged Hulāku to conquer Alamut but also to attack Baghdād.  They claim that Hulāku had originally decided to invade Constantinople,  but Tusi encouraged him to attack Baghdād. In contrast to the argument of Husām al-Din Munajjim, a Sunni astrologer and consultant in the court of Hulāku, who insisted that invading would cause the corruption of the entire world, Tusi argued that there would not be any problem.
Tusi reminded Hulāku that both Abbasid and non-Abbasid caliphs had been killed in the past without dire results. He added that the Abbasid caliph Maímun had killed his brother Amin and Mutawakkil, another caliph, had been assassinated by some of his military commanders and even his own son without upsetting the world order. The killing of Musntasir and Muʻtazz occurred without releasing universal corruption into the world.
Tusiís suggestion to Hulāku was not merely the result of an astrological interpretation of the stars. As an Imāmi scholar he did not accept the legal authority that declared the Abbāsid caliphs to be the religious leaders of the Muslim community. His letter to Baghdād, asking Ibn al-ʻAlqami to cooperate with him in converting the Abbāsid caliph to the Shiʻi doctrine, shows his discontent with caliphal religious authority as early as the first half of the thirteenth century.
After Hulāku conquered Baghdād, he hesitated to kill Mustaʻsim (d. 656) due to Munajjimís prediction that killing the vicegerent of the Prophet Muhammad (S) would result in disaster. Again Tusi promised that nothing would happen if the Abbasid caliph was killed and finally, in 656 A.H., the last Abbasid caliph was executed.
Other sources suggest that Tusi did not encourage the assassination of the caliph; rather. his support of Hulāku was a way to assist scholars and innocent people.  By holding an important position in Hulakuís court, he was able to restrain some of the Mongol leaderís excesses.
At this time, Mustansirís vizier was a Shiʻi named Ibn al-ʻAlqami (d. 656). He had had some covert relations with Tusi while the latter was living among the Seveners. It is believed that Ibn al-ʻAlqami also wrote a letter to Hulāku, telling him he need not be afraid to come to Baghdād.  The fact that he was appointed as the ruler of Baghdād by Hulāku after the Mongol leader had left the city lends some support to this idea.
Was Tusiís advice to Hulāku, perhaps aided and abetted by Ibn al-ʻAlqami, the only reason or even the main reason, for the collapse of the Abbasid caliphate? As Hairi mentions in his analysis of Tusiís role in the conquest of Baghdād, contemporary sources make no allusion to any political impact made by Tusi.
Sources such as the Al-Ādāb al-Sultāniyya, (al-Fakhri) (701/1301) of Ibn TaqTaq or the Mukhtasar of Abu al-Fidāí (d. 732/1331), as well as Tusiís own report about the conquest of Baghdād do not mention anything about Tusiís role. Tārikh-i Vassāf (728/1327) and Jāmiʻ al-Tawārikh (710/1310) only point out that Tusi predicted that the Mongol leader would replace the caliph. 
One of the main goals of the Mongols from the early period of their dominance was to open the gates of Baghdād. They attempted to invade Baghdād several times, but they were defeated. Manku Qāíān came to power during the period that the Crusaders were fighting the Mamluks in Egypt and Syria. Having received complaints from both Mongolian commanders and some of the ʻulamā who were under the pressure of Ismāʻili terrors and the ill treatment of the Abbāsids, the great Khān asked his brother Hulāku to invade the Islamic lands. Moreover, an agreement with King Hethum I of Armenia motivated the great Khān to expand his conquest to include Egypt and Syria. 
According to Cahen, Hethum I, had acted as the precursor of the Mongols on the shores of the Mediterranean against the Muslims of Syria and Asia Minor. His actions were, in fact, the result of favorable impressions sent to him by his eastern co-religionists. 
Hulāku began his mission by attacking the forts of the Assassins. Once he had invaded the Assassins, he moved toward Baghdād with Tusi as his consultant. Whether Tusi himself decided to be in the court of the Mongols or whether the Mongols forced him to do so is still disputable. In addition to the external threats, the Abbāsid caliphate had its internal problems rooted in the weakness and the corruption of the caliphate. 
Although Tusi did not accept the Abbāsid caliphate as legal authority, why would he prefer the secular authority of the Mongols? Did not Tusi, by encouraging Hulāku, actually participate in killing Muslims and destroying Muslim centers?
Attributing the fall of the caliphate to a single cause or a single person is a simplified interpretation of a complicated situation. Tusi witnessed the pre-Mongol conflicts and realized that the Mongol invasion of the Islamic world was inevitable.
Considering the internal and external situations of the Islamic world, the Mongols had already reached the conclusion that they had to start implementing their policies to conquer the world. The last and the most necessary choice that remained for the scholar was a limited and carefully planned cooperation with the Mongol troops.
Through his association with Hulāku, he could obtain a high position in the Ilkhānís court and play a constructive role in his policies. By using his influence with Hulāku, Tusi hoped to persuade the Mongol leader to act in the interests of the Muslims. Alone among Muslim scholars, Tusi noticed that the Mongol invasion was not ideological.
The Mongols invaded the Islamic lands in order to spread their power over a vast territory. Since their religion, which combined both pagan and shamanistic beliefs, was not likely to be an alternative to Islam, scholars like Tusi were able to use their presence as an instrument to save Islam. Vladimir Minorsky remarks that since the Mongolsí beliefs were vague and primitive, there was no chance for their propagation among the conquered population. Hence they were tolerant toward the other religions.  Dawson also maintains that during the reign of Chingiz Khān, it was a part of his law that all religions were to be respected without favouritism. 
After the fall of the Ismāʻilis and the Abbāsid caliphate, the flexible atmosphere allowed people a free choice in religion. Tusiís position at the court of Hulāku attracted the Muslim scholars from many places to one center and led to the revival of the Islamic sciences. Although Tusi paid special attention to the Imāmi sect and immediately after the fall of Baghdād visited Hilla, the very center of Imāmi scholarship, his main attempts were never limited to a particular group.
He not only invited the scholars of all sects to cooperation together at the school of Marāgha, but also spent Awqāf (endowments) to sponsor all Muslim scholars.
Tusiís Cultural influence
In spite of the bitter accusations hurled at Tusi for the role he was believed to have played in the fall of Baghdād and the massacre of Muslims, study of that crucial situation shows that without the support of a strong Muslim state, individuals such as Tusi could do nothing to prevent the Mongols from achieving their destructive goals. However, Tusiís influence on the continuation and revival of Islamic scholarship was more effective than his impact, if any at all, on the fall of Baghdād.
As an outstanding Islamic scholar who may be placed beside distinguished thinkers like al-Fārābi, Ibn Sinā, and al-Biruni, Tusi was an exception in a highly crucial period. His significant role in holding and reviving the Islamic civilization by obtaining the favor of Hulāku should not be ignored.  Despite his critical evaluation of Tusi, Arberry gives the following account of Tusiís cultural role: The Mongols, like their twentieth century disciples, knew how to handle and exploit to their own ends men of that caliber; and in the end, whether out of conviction or statecraft, the Ilkhāns accepted Islam and Muslim civilization was revived in Persia and Iraq.
That such a renaissance could take place at all, after the chaos and slaughter of the preceding years, was in large measure due to the collaboration of such as Nasir al-Din Tusi and Shams al-Din Juvaini, brother of the well-known historian and head of the administration of Persia under Mongol rule in the reigns of Hulāku (to 1265), Abākā (1265-82) and Ahmad (1282-4).
Apart from numerous writings in various fields of Islamic scholarship, Tusi made unique contributions in astronomy. After the fall of Baghdād, his main concern was to establish the school of Marāgha. His scientific center in Marāgha was so attractive that scholars, both Muslims and non-Muslims, came from all over the world to study and research there.
In addition to Muslim scholars, philosophers and scientists, Chinese astronomers were invited to work at the school of Marāgha. For the last eighteen years of his life, Tusi was engaged in building this observatory. His contribution in astronomy was so important that even modern scholars have benefited from his findings.  In appreciation of his scientific findings, NASA nominated one of the craters on the moon to commemorate him. 
a. Tusi and the school of Marāgha
Despite the socio-political role he was forced to play by circumstances, Tusiís main contributions and interests were intellectual. After Jundi Shāpur with its legacy of a pre-Islamic university and the Nizāmiyya established by Nizām al-Mulk in Baghdād, the school of Marāgha was the most important madrasa in the Islamic world. Although this school was first founded as a center for astronomy and mathematics, it then became an important center for all Islamic sciences. The first observatory in the Islamic world was established at the command of al-Maímun, an Abbasid caliph.
By the end of the third century A.H. other observatories had been founded in Syria, Egypt and Baghdād. Tusiís observatory, established at Marāgha in 617/1285, was the most fascinating and advanced.  Astronomers were invited to study there from the east and the west while the school of Marāgha incorporated various branches of Islamic sciences.
Students of astronomy were called from as far away as China to study at the school of Marāgha. The observatory of Marāgha was unique for almost three centuries.  Tusi actually established in Marāgha the prototype of the modern university. Its library was composed of more than 400,000 volumes, collected from different cities like Transoxiana, Khurāsān, Baghdād, Musil and Damascus which were the victims of the early Mongol invasions. 
The school of Marāgha incorporated different sections (dār al-hikma) devoted to philosophy, medicine, jurisprudence (Fiqh), and hadith. Interestingly, they each had a different priority and received their funding based on this hierarchy. Researchers in Dār al-Hikma received three dirhams for every 48 hour period, those in Dār al-Tibb received two dirhams, those in Dār al-Fiqh one dirham, while those in Dār al-Hadith received only half a dirham. 
The main source of the income to pay these expenses was the Awqāf under Tusiís supervision. The distinguishing characteristic of the Marāgha School was its variety of subjects and the priority given to some of the branches of Islamic sciences. These characteristics might explain the accusations which claimed that Tusi was using Muslim endowments not for fiqh but for Greek philosophy and other sciences.
One of Tusiís outstanding characteristics was that although most of his life was spent among either Assassins or Mongols, surrounded by wars, attacks and retaliations, all of which were conditions unsuitable for study and research, he had an effective influence on intellectual development. This influence was most prominent in astrology, mathematics, philosophy and theology.
According to Strothmann, Tusiís fame outside Shiʻi circles was due to his books and research in the exact sciences, namely medicine, physics, mathematics and particularly astrology and astronomy. Another important aspect of Tusi was his flexibility and openness in his intellectual relations with all Muslim scholars even non- Shiʻa.
He did not allow his devotion to his own sect to cut him off from scholarly connections with non-Imāmi ʻulamā.  This unique characteristic enabled him to influence and be influenced by many contemporary scholars.
b. Reviving the Imāmi theology (particularly the issue of the Imāmate)
One of the most important aspects of Tusiís intellectual career was his significant role in reformulating the Shiʻi theology, combining the Peripatetic style with what he had grasped from his Shiʻi ideology to give new understanding to the issue of the Imamate. For example, Tajrid al-ʻAqāíid, commented on by several Shiʻi scholars, and Qawāʻid al-ʻAqāid were written based on an Imāmi point of view.
In Fusul Nasiriyya he explicitly disagreed with the philosophic and determinative Ashʻarite point of view while in Talkhis al-Muhassal he critiqued the K. al-Muhassal of Fakhr al-Din al-Rāzi. His Masāriʻ al-Masāriʻ was a critical commentary on K. al-Musāriʻa of M. ʻAbd al-Karim al-Shahrastāni which refuted Ibn Sināís ideas. Several other treatises were written based on either the Imāmi or the Ismāʻili points of view. 
More important is a treatise on the issue of the Imāmate republished on the occasion of the commemoration of his 7th anniversary. His main goal in these works was to rationalize what previously had been presented by other Imāmi scholars in a more or less traditionalist point of view. This characteristic will be clearer if his method is compared with that of Nawbakhti in K. al-Yāqut and those of Shaykh al-Mufid (336-413) and Seyyed Murtazā (355-436) against Bāqilāni. 
In the history of Imāmi theology, Tusi reformulated this branch of thought from traditionalism to rationalism. His doctrines put him in a position distinct from both Ismāʻilis and Sunnis. Tajrid al-Iʻtiqād, Fusul Nasiriyya and the Treatise on the Imamate were written using an Imāmi methodology. In his Qawāʻid, particularly on the issue of the Imamate, he tried to present various ideas according to Imāmis, Zaydis, Extremists (Ghulāt), Kaysānis and Sunnis without insisting on any particular idea. 
c. Tusi and philosophy, mysticism and ethics
As a philosopher, Tusi was greatly influenced by Ibn Sinā (980-1037). He supported Ibn Sināís ideas by refuting critiques written against him.  He spent about twenty years writing a commentary on the Al-Ishārāt wa al-Tanbihāt (Safadi, Al-Wāfi bi al-Wafayāt).
However, he disagreed with Ibn Sinā on the issue of Godís knowledge and approached it from an illuminationist (Ishrāqi) point of view. Like Suhrawardi al-Maqtul (d. 587/1191), he believed that Godís knowledge is a kind of illuminational relation (izāfa ishrāqiyya). 
Tusiís mystical background goes back to his early learning period in Nishāpur when he first visited Farid al-Din Saʻid Ibn Yusif Ibn ʻAli ʻAttār (513-617A.H) and was attracted to his ideas.  He treated mystics with respect and honor. At the time of the conquest of Baghdād, he and Hulāku visited Abā al-Fuqarāí Muhammad b. ʻAbd al-ʻAziz, one of the greatest mystics of the time, at his zāwia (privte place for the Sufiís practices and contemplation).
When Abā al-Fazl Jaʻfar b. ʻAli, known as al-Muítaman al-Sufi al-Baghdādi, went to Marāgha to visit Tusi, Tusi assigned 100 dinārs to him each year from the awqāf of Baghdād.  In addition, Tusi had a warm relationship with Sadr al-Din Qunyawi (d. 673) and Jamāl al-din ʻAyn al-Zamān Jili (d. 651) - two of the great mystics of the time -through various letters. 
In the meantime, Tusi himself wrote mystical treatises. His Awsāf al-Ashrāf written at the request of Hulākuís vizier Shams al-Din Muhammad Juvayni (d. 681) is a written price with a mystical methodology about the spiritual journey (Sayr wa Suluk). 
In spite of his considerable devotion to the twelve Imāms, his deep respect for Hallāj distinguished him from most of the other Shiʻa.  R. Āghāz va Anjām, also entitled as Tadhkira, has an Ismāʻili basis and deals with demonstrating the principles of beliefs in a mystical way. 
Why was the intellectual atmosphere of Tusiís time dominated by mystical thought and the Ismāʻili esoteric understanding of Islamic belief? Although this current of mystical thought was mainly centered at the court of the Saljuks of Rum, other parts of the Islamic world were not totally exempt from this trend.
The esoteric doctrines of the Ismāʻilis might have been a reaction against Sunni orthodox Islam, first formed by the Fatimids of Egypt and then by the Nazāri Ismāʻilis of Iran and Syria. They were the opposite side to the extreme traditionalism held by the Abbasid caliphs and their political supporters such as the Saljuks.
Nonetheless, this pole of esoteric thought collapsed officially upon the destruction of the Ismāʻili fortresses. As far as an extension of pure mystical thought is concerned, one can find various interpretations. Some believe that mystical tendencies are rooted in a weakness of the political authority or material disadvantages.
When the people are deprived of worldly advantages, they tend to focus on the afterlife. However, the very core of mystical thought and its flourishing took place at the powerful and wealthy court of the Saljuks of Rum. By the time of the Mongol invasion, the Saljuks of Rum were the only shelter for Muslim scholars under the pressure of Mongol attacks. Since the most dominant figure at this court was Sadr al-Din Qunyawi, the immediate disciple of Ibn ʻArabi, his colleagues were mostly mystics.
Undoubtedly, one main reason for the spread of mystical thought at this time was the immigration of Ibn ʻArabi from Andalusia to Anatolia. His school of thought was so influential that for several centuries, it remained active throughout the Islamic world. The reasons for Ibn ʻArabiĎs departure from Andolusia remain unclear. His migration may have been the result of a dream which inspired him to leave Andalusia.
On the other hand, he may have wanted to leave Islamic lands dominated by Māliki ideas and the Peripatetic philosophy which denied an esoteric interpretation of Islamic knowledge. What was it about the eastern part of the Islamic world which attracted Ibn ʻArabi and encouraged him to establish his own school of thought there? What was the real background in the eastern part of the Islamic lands which caused the development of mystical thought? Can we find any socio-political reason for this flourishing mysticism? These questions remain unanswered.
Tusiís writings in ethics were written mainly while he was living among the Ismāʻilis. At the request of Nāsir al-Din ʻAbd al-Rahim Ibn Abi Mansur, the ruler (muhtasham) of Quhistān, he rewrote and corrected Tahdhib al-Akhlāq wa Tathir al-Aʻrāq by Abu ʻAli Miskawayh (d.421/1029) and called it as Akhlāq-i Nāsiri.  Then he translated the K. Adab al-Saghir of Ibn al-Muqaffaʻ into Persian. 
A Comparison between Tusi and Nizām al-Mulk
Since Nizām al-Mulk and Nasir al-Din Tusi were both viziers in very different Iranian Empires, it is interesting to compare their decisive roles in different aspects. In addition to their political role, they both played a constructive role in reviving the intellectual atmosphere by re-establishing madrasas.
They both used waqf as the main source to sponsor these madrasas. However, they were also dissimilar. For example, Tusi wrote more than 56 different books and treatises.  Nizām al-Mulk, however, published few writings. Tusiís political attitude derived from his Shiʻi ideas while that of Nizām al-Mulk was rooted in Sunni Islam.
The difference appeared in supporting or abolishing the idea of the caliphate in both theory and practice. While Nizām al-Mulk believed in the legitimacy of the Abbasidís authority and motivated the Saljuks to support the Abbasid caliphs, Tusi accompanied Hulāku to invade Baghdād and destroy the caliphate. 
In spite of their emphasis on reviving intellectual and religious thought, the Nizāmiyya of Baghdād was explicitly a center of Shāfiʻi fiqh and Ashʻrite theology whereas the Nasiriyya of Marāgha incorporated a wider field of Islamic sciences. Moreover, Tusi did not announce that the orthodox fiqh and theology must be Imāmi.
The library of Marāgha was more important than that of the Nizāmiya; it contained a considerable number of books since it was a collection of the writings from Baghdād, Syria, and the Arabian Peninsula. In addition, those books which were gathered from the eastern parts of the Mongol Empire were added to the collection.
Another important difference between the two Muslim viziers was their political involvement. After the collapse of the Abbasid caliphate, Tusi addressed only two important political letters to the rulers of Shāmāt and Halab, - al-Malik al-Nāsir, Sayf al-Din b. Yaghmur and ʻAlāí al-Din al-Qushaymuri, respectively  - and devoted most of his concerns to intellectual affairs, particularly the establishment of the observatory of Marāgha. 
He traveled to Baghdād and other cities with Hulāku and his successor Abāqākhān only to visit ʻulamā and raise the awqāf which he then spent on the school of Marāgha.  The main feature of Nizām al-Mulkís career, on the other hand, was his involvement with socio-political affairs, as he was one of the most important political figure of his time.
Living in one of the most difficult periods of Islamic history, Nasir al-Din Tusi was able to play a decisive role in maintaining and even developing the stream of Islamic civilization in its various aspects. The variety of his writings, his openness toward Muslim scholars from different schools of thought, and his willingness to examine Islamic knowledge through both its esoteric and exoteric ways are some characteristics that distinguished Tusi not only from other scholars of his generation but also among Muslim thinkers throughout the history of Islamic civilization.
His most positive contributions were probably the establishment of the school of Marāgha, supervising the Awqāf property of the vast portion of the Muslim world and spending a considerable amount of it in administrating the school of Marāgha. His long-lasting stay among the Seveners, and his involvement in the court of the Mongols could never extinguish the light of Tusiís enlightenment. Yet he was able to revise his Imāmi ideology while reviving Islamic knowledge in its comprehensive form.
Although the school of Marāgha concentrated on astrology and astronomy as the fields which interested the Mongols, it also covered different aspects of Islamic knowledge. It can even be considered as the prototype of a modern university. In addition to his unique expertise in astrology, Tusi was a distinguished scholar in other fields of Islamic knowledge.
Philosophy, theology, ethics, mysticism, medicine and pure sciences are fields that were creatively touched by this medieval thinker. Interestingly, in theology he focused on the issue of the Imamate, as the main concern of the Ismāʻilis and an alternative for the institution of the Abbasid caliphate. He may have had a socio-political concern which led him to deal with this issue in his theological writings. Both in theory and practice, Tusi was positively involved with mysticism.
This involvement indicates the dominance of mystical thought at that period. His numerous writings in this field, his written relationships with his contemporary mystics, and his respectful treatment of the true mystics of his time are clues to the characteristics which created a unique personality out of an individual born into a zāhiri Imāmi family. Tusi was, clearly, a unique Muslim scholar rather than a mere politician.