Muḥammad ibn Muḥammad ibn al-Ḥasan al-Ṭūsī (1201–1274; AH 598–673), commonly known as Naṣīr al-Dīn al-Ṭūsī (; ) or simply (al-)Tusi, was a Persian polymath, architect, philosopher, physician, scientist, and theologian, as well as a prominent Shiʿite scholar.Multiple sources:
Rodney Collomb, The Rise and Fall of the Arab Empire and the Founding of Western Pre-eminence, Spellmount, 2006, p. 127. Seyyed Hossein Nasr, Islamic Philosophy from Its Origin to the Present: Philosophy in the Land of Prophecy, SUNY Press, 2006, , p. 199. Seyyed H. Badakhchani, Contemplation and Action: The Spiritual Autobiography of a Muslim Scholar: Nasir al-Din Tusi, I. B. Tauris, 1999, , p. 1. He wrote extensively on mathematics, engineering, prose, mysticism, philosophy, theology, and the sciences, and is widely regarded as one of the greatest scientists of medieval Islam.
Born in Ṭūs, from which his name derives, al-Tusi later worked under an Ismāʿīlī ruler at Alamūt, the centre of the Nizārī Ismāʿīlīs, and produced Ismāʿīlī works that acquired considerable authority, although his own personal religious allegiance during this period remains uncertain. When Hūlāgū Khān and the Mongols captured Alamūt in 1256, al-Tusi entered Hūlāgū's service as an astrologer and was instrumental in saving numerous libraries from destruction.
Al-Tusi made significant contributions across several scientific disciplines. In astronomy, he compiled highly accurate tables of planetary motion, developed an improved planetary model, criticized aspects of Ptolemaic astronomy, and compiled the astronomical tables known as the Zīj al-Khānī. He also introduced the mathematical device later known as the "Ṭūsī couple". His work extended to logic, mathematics, biology, chemistry, and especially trigonometry, which he is often credited with establishing as an independent mathematical discipline rather than merely an instrument of astronomy. The Muslim historian Ibn Khaldun regarded him as the greatest of the later non-Arab scholars.James Winston Morris, "An Arab Machiavelli? Rhetoric, Philosophy and Politics in Ibn Khaldun’s Critique of Sufism", Harvard Middle Eastern and Islamic Review 8 (2009), pp 242–291. excerpt from page 286 (footnote 39): "Ibn Khaldun’s own personal opinion is no doubt summarized in his pointed remark (Q 3: 274) that Tusi was better than any other later non-Arab scholar". Original Arabic: Muqaddimat Ibn Khaldūn : dirāsah usūlīyah tārīkhīyah / li-Aḥmad Ṣubḥī Manṣūr-al-Qāhirah : Markaz Ibn Khaldūn : Dār al-Amīn, 1998. . Excerpt from Ibn Khaldun is found in the section: الفصل الثالث و الأربعون: في أن حملة العلم في الإسلام أكثرهم العجم (On how the majority who carried knowledge forward in Islam were Non-Arabs. In this section, see the sentence where he mentions Tusi as more knowledgeable than other later non-Arabs ('Ajam) scholars: . و أما غيره من العجم فلم نر لهم من بعد الإمام ابن الخطيب و نصير الدين الطوسي كلاما يعول على نهايته في الإصابة. فاعتير ذلك و تأمله تر عجبا في أحوال الخليقة. و الله يخلق ما بشاء لا شريك له الملك و له الحمد و هو على كل شيء قدير و حسبنا الله و نعم الوكيل و الحمد لله. His astronomical work has also been discussed as a possible influence on Copernicus and the development of Copernican heliocentrism.
A prolific author on subjects ranging across the sciences, philosophy, theology, ethics, and mysticism, al-Tusi's most enduring works include al-Akhlāq al-Nāṣiriyya ("The Nasirean Ethics", 1235) and Tajrīd al-Iʿtiqādāt ("The Definition of the Articles of Faith"). His broad intellectual output, together with his mathematical and astronomical innovations, secured his reputation as one of the major polymaths of the medieval Islamic world.
Biography Nasir al-Din Tusi was born in the city of Tus in medieval Khorasan (northeastern Iran) in the year 1201 and began his studies at an early age. In Hamadan and Tus, he studied the Quran, Hadith, Ja'fari jurisprudence, logic, philosophy, mathematics, medicine, and astronomy.Dabashi, Hamid. "Khwajah Nasir al-Din Tusi: The philosopher/vizier and the intellectual climate of his times". Routledge History of World Philosophies. Vol I. History of Islamic Philosophy. Seyyed Hossein Nasr and Oliver Leaman (eds.) London: Routledge. 1996. p. 529
He was born into a Shī‘ah family and lost his father at a young age. Fulfilling the wish of his father, the young Nasir took learning and scholarship very seriously and traveled far and wide to attend the lectures of renowned scholars and acquired knowledge, an exercise highly encouraged in his Islamic faith. At a young age, he moved to Nishapur to study philosophy under Farid al-Din Damad and mathematics under Muhammad Hasib.Siddiqi, Bakhtyar Husain. "Nasir al-Din Tusi". A History of Islamic Philosophy. Vol 1. M. M. Sharif (ed.). Wiesbaden:: Otto Harrossowitz. 1963. p. 565 He met also Attar of Nishapur, the legendary Sufi master who was later killed by the Mongols, and he attended the lectures of Qutb al-Din al-Misri – a student of Al-Razi.
Nasir-al-Din Tusi writes in his work, Desideratum of the Faithful (Maṭlūb al-muʾminīn),“To become people of spiritual reality, it is incumbent to fulfill the symbolic elucidation (ta'wīl) of the seven pillars of the religious law (sharīʿat)”. He also explains that fulfilling the religious law is much easier than fulfilling its spiritual interpretation.
He explains in his book Aghaz u anjam that the sacred accounts of history that we perceive within the bounds of space and time symbolize events that have no such restrictions. They are only expressed in this way so that humans are able to comprehend them.
In Mosul, al-Tusi studied mathematics and astronomy with Kamal al-Din ibn Yunus (d. AH 639 / AD 1242), a pupil of Sharaf al-Dīn al-Ṭūsī. Later on he corresponded with Sadr al-Din al-Qunawi, the son-in-law of Ibn Arabi, and it seems that mysticism, as propagated by Sufi masters of his time, was not appealing to him. Once the occasion was suitable, he composed his own manual of philosophical Sufism in the form of a small booklet entitled Awsaf al-Ashraf, or "The Attributes of the Illustrious".
As the armies of Genghis Khan swept his homeland, he was employed by the Nizari Ismaili state and, while moving from stronghold to stronghold, made his most important contributions in science,Peter Willey, The Eagle's Nest: Ismaili Castles in Iran and Syria, (I.B. Tauris, 2005), 172. first in those of the Quhistan region under muhtasham Nasir al-Din Abu al-Fath Abd al-Rahim ibn Abi Mansur (where he wrote the Nasirean Ethics in 1235). He was later sent to the major castles of Alamut and Maymun-Diz to continue his career under Nizari Imam Ala al-Din Muhammad. He was captured after the capitulation of Maymun-Diz to the Mongol forces under Hulegu Khan, a grandson of Genghis Khan.Michael Axworthy, A History of Iran: Empire of the Mind, (Basic Books, 2008), 104.
Nasir al-Din Tusi’s autobiography, The Voyage (Sayr wa-Suluk) explains that a literary devastation such as the devastation of the Alamut libraries in 1256 would not waver the spirit of the Nizari Ismaili community because they give more importance to the “living book” (the Imam of the Time) rather than the “written word”. Their hearts are attached to the Commander of the Believers (amir al-mu'minin), not just the “command” itself. There is always a present living Imam in world, and following him, a believer will never go astray.
Role during the Mongol invasion of Baghdad In 1256, al-Tusi was in the castle of Alamut when it was attacked by the forces of the Mongol leader Hulegu. Some sources claim that al-Tusi betrayed the defences of Alamut to the invading Mongols. After his forces destroyed Alamut, Hulegu, who was himself interested in the natural sciences, treated al-Tusi with great respect, appointing him as scientific adviser and a permanent member of his inner council. To great controversy, it is widely assumed Tusi was with the Mongol forces under Hulegu when they attacked and massacred the inhabitants of Baghdad in 1258 and he played an essential role in ending of the Abbasid empire. After the siege of Baghdad, he was entrusted with the administration of religious endowments and traveled extensively to both Sunni and Shiʿi institutions. In this capacity, he is credited with helping preserve religious foundations, libraries, and scholarly institutions during the period of Mongol rule. Through his scholarly and administrative influence, al-Tusi helped strengthen Twelver Shiʿi intellectual life and institutional presence in Persia and Iraq, without formally transforming the sectarian order of the state.
Works Tusi has about 150 works, of which 25 are in Persian and the remaining are in Arabic, and there is one treatise in Persian, Arabic and Turkish.Seyyed Hossein Nasr. The Islamic Intellectual Tradition in Persia. Curson Press, 1996. See p. 208: "Nearly 150 treatises and letters by Nasir al-Din al-Tusi are known, of which twenty-five are in Persian and the rest in Arabic. There is even a treatise on geomancy that Tusi wrote in Arabic, Persian, and Turkish, demonstrating his mastery of all three languages. It is said that he also knew Greek. His writings concern nearly every branch of the Islamic sciences, from astronomy to philosophy and from the occult sciences to theology."
Sayr wa-Suluk (The Voyage) – Autobiography Kitāb al-Shakl al-qattāʴ – Book on the complete quadrilateral. A five-volume summary of trigonometry. Al-Tadhkirah fi'ilm al-hay'ah – A memoir on the science of astronomy. Many commentaries were written about this work called Sharh al-Tadhkirah (A Commentary on al-Tadhkirah) – Commentaries were written by Abd al-Ali ibn Muhammad ibn al-Husayn al-Birjandi and by Nazzam Nishapuri. Akhlaq-i Nasiri – A work on ethics. al-Risalah al-Asturlabiyah – A Treatise on the astrolabe. Zij-i Ilkhani (Ilkhanic Tables) – A major astronomical treatise, completed in 1272. Sharh al-Isharat (Commentary on Avicenna's Isharat) Awsaf al-Ashraf – a short mystical-ethical work in Persian. Tajrīd al-Iʿtiqād (Summation of Belief) – A commentary on Shi'a doctrines. Talkhis al-Muhassal (summary of summaries). Maṭlūb al-muʾminīn (Desideratum of the Faithful) Aghaz u anjam – Esoteric interpretation of the Quran
An example from one of his poems: Anyone who knows, and knows that he knows, makes the steed of intelligence leap over the vault of heaven. Anyone who does not know but knows that he does not know, can bring his lame little donkey to the destination nonetheless. Anyone who does not know, and does not know that he does not know, is stuck forever in double ignorance.
Achievements
During his stay in Nishapur, Tusi established a reputation as an exceptional scholar. Tusi’s prose writing, which numbers over 150 works, represents one of the largest collections by a single Islamic author. Writing in both Arabic and Persian, Nasir al-Din Tusi dealt with both religious ("Islamic") topics and non-religious or secular subjects ("the ancient sciences").H. Daiber, F.J. Ragep, "Tusi" in Encyclopaedia of Islam. Edited by: P. Bearman, Th. Bianquis, C.E. Bosworth, E. van Donzel and W.P. Heinrichs. Brill, 2007. Brill Online. Quote: "Tusi's prose writings, which number over 150 works, represent one of the largest collections by a single Islamic author. Writing in both Arabic and Persian, Nasir al-Din dealt with both religious ("Islamic") topics and non-religious or secular subjects ("the ancient sciences")." His works include the definitive Arabic versions of the works of Euclid, Archimedes, Ptolemy, Autolycus, and Theodosius of Bithynia.
Astronomy
Tusi convinced Hulegu Khan to construct an observatory for establishing accurate astronomical tables for better astrological predictions. Beginning in 1259, the Rasad Khaneh observatory was constructed in Azarbaijan, south of the river Aras, and to the west of Maragheh, the capital of the Ilkhanate Empire.