Nasir Al-Din Al-Tusi
(1201-1274 C.E.)
Abu Jafar Muhammad Ibn Muhammad Ibn al-Hasan Nasir al-Din
alTusi was born in Tus (Khurasan) in 1201 C.E. He learnt sciences and philosophy
from Kamal al-Din Ibn Yunus and others. He was one of those who were kidnapped
by Hasan Bin Sabah's agents and sent to
Almut, Hasan's stronghold. In 1256 when Almut was conquered
by the Mongols, Nasir al-Din joined Halagu's service. Halagu Khan was deeply
impressed by his knowledge, including his astrological competency; appointed
him as one of his ministers, and, later on, as administrator of Auqaf. He was
instrumental in the establishment and progress of the observatory at Maragha.
In his last year of life he went to Baghdad and died there.
Although usually known as Nasir al-Din al-Tusi, his proper name
was Muhammad ibn Muhammad ibn al-Hasan al-Tusi. In fact al-Tusi was known by a
number of different names during his lifetime such as Muhaqqiq-i Tusi,
Khwaja-yi Tusiand Khwaja
Nasir. Al-Tusi was born in Tus, which lies close to Meshed
in northeastern Iran high up in the valley of the Kashaf River. He was born at
the beginning of a century which would see conquests across the whole of the
Islamic world from close to China in the east to Europe in the west. It was the
era when the vast military power of the Mongols would sweep across the vast
areas of the Islamic world displaying a bitter animosity towards Islam and cruelly
massacring people. This was a period in which there would be little peace and
tranquillity for great scholars to pursue their works, and al-Tusi was
inevitably drawn into the conflict engulfing his country.
In Tus, al-Tusi's father was a jurist in the Twelfth Imam School.
The Twelfth Imam was the main sect of Shi'ite Muslims and the school where
al-Tusi was educated was mainly a religious establishment. However, while
studying in Tus, al-Tusi was taught other topics by his uncle which would have
an important influence on his intellectual development. These topics
included logic, physics and metaphysics while he also
studied with other teachers learning mathematics, in particular algebra and
geometry.
In 1214, when al-Tusi was 13 years old, Genghis Khan, who was
the leader of the Mongols, turned away from his conquests in China and began
his rapid advance towards the west. It would not be too long before al-Tusi
would see the effects of these conquests on his own regions, but before that
happened he was able to study more advanced topics. From Tus, al-Tusi went to Nishapur
which is 75 km west of Tus. Nishapur was a good choice for al-Tusi to complete
his education since it was an important centre of learning. There al-Tusi
studied philosophy, medicine and mathematics. In particular he was taught
mathematics by Kamal al-Din ibn Yunus, who himself had been a pupil of Sharaf
al-Din al-Tusi. While in Nishapur al-Tusi began to acquire a reputation as an
outstanding scholar and became well known throughout the area.
The Mongol invasion reached the area of Tus around 1220 and
there was much destruction. Genghis Khan turned his attention again towards the
east leaving his generals and sons in the west to continue his conquests. There
was, amid the frequent fighting in the region, peaceful havens which attracted
al-Tusi.
The Assassins, who practised an intellectual form of
extremist Shi'ism, controlled the castle of Alamut in the Elburz Mountains, and
other similar impregnable forts in the mountains. When invited by the Isma'ili
ruler Nasir ad-Din 'Abd ar-Rahim to join the service of the Assassins, al-Tusi
accepted and became a highly regarded member of the Isma'ili Court. Whether he
would have been able to leave, had he wished to, is not entirely clear.
However, al-Tusi did some of his best work while moving
round the different strongholds, and during this period he wrote important
works on logic, philosophy, mathematics and astronomy. The first of these
works, Akhlaq-i nasiri, was written in 1232.
It was a work on ethics which al-Tusi dedicated to the
Isma'ili ruler Nasir ad-Din 'Abd ar-Rahim.
In 1256 al-Tusi was in the castle of Alamut when it was attacked
by the forces of the Mongol leader Hulegu, a grandson of Genghis Khan, who was
at that time set on extending Mongol power in Islamic areas. Some claim that
al-Tusi betrayed the defences of Alamut to the invading Mongols. Certainly
Hulegu's forces destroyed Alamut and, Hulegu himself being himself interested
in science, he treated al-Tusi with great respect. It may be that indeed
al-Tusi felt that he was being held in Alamut against his will, for certainly
he seemed enthusiastic in joining the victorious Mongols who appointed him as
their scientific advisor. He was also put in charge of religious affairs and
was with the Mongol forces under Hulegu when they attacked Baghdad in 1258.
Al-Musta'sim, the last Abbasid caliph in Baghdad, was a weak
leader and he proved no match for Hulegu's Mongol forces when they attacked Baghdad. After having
laid siege to the city, the Mongols entered it in February 1258 and
al-Musta'sim together with 300 of his officials were murdered. Hulegu had
little sympathy with a city after his armies had won a battle, so he burned and
plundered the city and killed many of its inhabitants.
Certainly al-Tusi had made the right move as far as his own
safety was concerned, and he would also profit scientifically by his change of
allegiance. Hulegu was very pleased
with his conquest of Baghdad and also pleased that such an eminent scholar as
al-Tusi had joined him. So, when al-Tusi presented Hulegu with plans for the
construction of a fine Observatory, Hulegu was happy to agree.
Hulegu had made Maragheh his capital . Maragheh was in the Azerbaijan
region of northwestern Iran, and it was at Maragheh that the Observatory was to
be built. Construction of the Observatory began in 1259 west of Maragheh, and
traces of it can still be seen there today.
The observatory at Maragheh became operational in 1262. Interestingly
the Persians were assisted by Chinese astronomers in the construction and
operation of the observatory. It had various instruments such as a 4 metre wall
quadrant made from copper and an azimuth quadrant which was the invention of
Al-Tusi himself. Al-Tusi also designed other instruments for the
Observatory which was far more than a centre for astronomy.
It possessed a fine library with books on a wide range of scientific topics,
while work on science, mathematics and philosophy were vigorously pursued
there.
Al-Tusi put his Observatory to good use, making very
accurate tables of planetary movements. He published Zij-i ilkhani (the Ilkhanic
Tables), written first in Persian and later translated into
Arabic, after making observations for 12 years. This work
contains tables for computing the positions of the planets, and it also contains
a star catalogue. This was not the only important work which al-Tusi produced
in astronomy. It is fair to say that al-Tusi made the most significant
development of Ptolemy's model of the planetary system up to the development of
the heliocentric model in the time of
Coper nicus. In al-Tusi's major astronomical treatise, al-Tadhkira fi'ilm
al-hay'a(Memoir on astronomy) he:
... devised a new model of lunar motion, essentially
different from Ptolemy's. Abolishing the eccentric and the centre of
prosneusis, he founded it exclusively on the principle of eight uniformly
rotating spheres and thereby succeeded in representing the irregularities of lunar
motion with the same exactness as the "Almagest". His claim that the
maximum difference in longitude between the two theories amounts to 10 proves
perfectly true. In his model Nasir, for the first time in the history of
astronomy, employed a theorem invented by himself which, 250 years later,
occurred again in Copernicus, "De Revolutionibus", III 4. The theorem referred to in this quotation
concerns the famous "Tusi-couple" which resolves linear motion into
the sum of two circular motions. The aim of al-Tusi with this result was to
remove all parts of Ptolemy's system that were not based on the principle of
uniform circular motion. Many historians claim that the Tusi-couple result was
used by Copernicus after he discovered it in Al-Tusi's work, but not all agree;
see for example where it is claimed that Copernicus took the result from Proclus's
Commentary on the first book of Euclid and not from al-Tusi.
Among numerous other contributions to astronomy, al-Tusi calculated
the value of 51' for the precession of the equinoxes. He also wrote works on
astronomical instruments, for example on constructing and using an astrolabe. In logic al-Tusi followed the teachings of ibn
Sina (Avicenna).
He wrote five works on the subject, the most important of
which is one on inference. Street describes this as follows:-
Tusi, a thirteenth century logician writing in Arabic, uses
two logical connectives to build up molecular propositions: 'if-then', and 'either-or'.
By referring to a dichotomous tree, Tusi shows how to choose the proper
disjunction relative to the terms in the disjuncts.
He also discusses the disjunctive propositions which follow
from a conditional proposition.
Al-Tusi wrote many commentaries on Greek texts. These included
revised Arabic versions of works by Autolycus, Aristarchus, Euclid, Apollonius,
Archimedes, Hypsicles, Theodosius, Menelaus and Ptolemy. In particular he wrote
a commentary on Menelaus's Spherics, and Archimedes' On the sphere and
cylinder. In the latter work al-Tusi discussed objections raised by earlier
mathematicians to comparing lengths of
straight lines and of curved lines. Al-Tusi argues that
comparisons are legitimate, despite the objections that, being different entities,
they are incomparable.
Ptolemy's Almagestwas one of the works which Arabic
scientists studied intently. In 1247 al-Tusi wrote Tahrir al-Majisti (Commentary on the
Almagest) in which he introduced various trigonometrical techniques to
calculate tables of sines. As in the Zij-i Ilkhahial-Tusi gave tables of sines
with entries calculated to three sexagesimal places for each half degree of the
argument.
One of al-Tusi's most important mathematical contributions was
the creation of trigonometry as a mathematical discipline in its own right
rather than as just a tool for astronomical applications. In Treatise on the
quadrilateralal-Tusi gave the first extant
exposition of the whole system of plane and spherical
trigonometry.
This work is really the first in history on trigonometry as
an independent branch of pure mathematics and the first in which all six cases
for a right-angled spherical triangle are set forth.
This work also contains the famous sine formula for plane
triangles:
a/sin A=b/sin B =c/sin C
Another mathematical contribution was al-Tusi's manuscript,
dated 1265, concerning the calculation of n-th roots of an integer. This work
by al-Tusi is almost certainly not original but rather it is his version of
methods developed by al-Karaji's school. In the manuscript al-Tusi determined
the coefficients of the expansion of a binomial to any power giving the
binomial formula and the Pascal triangle relations between binomial
coefficients.
We should mention briefly other fields in which al-Tusi
contributed. He wrote a famous work on minerals which contains an interesting
theory of colour based on mixtures of black and white, and included chapters on
jewels and perfumes. He also wrote on medicine, but his medical works are among
his least important. Much more important were al-Tusi's contributions to philosophy
and ethics. In particular in philosophy he asked important questions on the
nature of space.
Al-Tusi had a number of pupils, one of the better known being
Nizam al-a'Rajwho also wrote a commentary on the Almagest.Another of his pupils Qutb ad-Din ash-Shirazi gave
the first satisfactory mathematical explanation of the rainbow. alTusi's
influence, which continued through these pupils, is summed up as follows:-
Al-Tusi's influence, especially in eastern Islam, was
immense. Probably, if we take all fields into account, he was more
responsiblefor the revival of the Islamic sciences than any other individual.
His bringing together so many competent scholars and scientists at Maragheh
resulted not only in the revival of mathematics and astronomy but also in the
renewal of Islamic philosophy and even theology.
He pioneered spherical trigonometry which includes six
fundamental formulas for the solution of spherical right-angled triangles. One
of his most important mathematical contributions was the treatment of
trigonometry as a new mathematical discipline. He wrote on binomial
coefficients which Pascal later introduced. (He can be called the "Father
of Trigonometry".) He was also an astronomer philosopher, and medical
scholar as well as a
Geometry
Trigonometry
Algebra
Hindu-Arabic Numerals and how they came into Europe as
"Arabic numerals" are explained. See other links at the bottom of
this site. Also see how "Hindu" numerals came to Persia and Arabia,
and then how "Arabic" numbers came into Europe.
Read an overview of "Arab Contributions to Medieval
mathematics". It includes the contributions of Al-Khwarizmi, Abu Kamil
Shuja (al'Hasib), Abu'l-Wafa, al-Karkhi, Omar Khayyam, and Al-Kashi.
Several biographies of scientists and mathematicians are
found on on the Muslim Scholars Homepage: Al-Khwarizmi, Al-Kindi, Omar Khayyam,
Al-Biruni, Nasir al-Din, and others.
Learn about Mathematicians born in Iraq, including Al
Khwarizmi.
Biographies of Mathematicians by Dr. Zahoor are listed.
Choose three or four of the most famous: al-Khwarizmi (algebra) [al-Khwarizmi
is also here], Omar Khyyam, al-Battani (trigonometry), al-Haitham (known as
Alhazen in the West, developed analytical geometry by establishing linkage
between algebra and geometry), al-Tusi (non-Euclidian geometry), and al-Biruni
(who determined the circumference of the earth).
See a chart comparing modern Arabic numerals with the
earlier Arabic numerals developed in the Middle Ages (and influenced by the
Hindu numerals with the concept of place value and the "zero").
Al-Khwarizmi (father of algebra); read another biography of
Al-Khwarizmi. Read about Al-Khwarizmi and see one of his famous works on
completing the square (shown below).
Arabic Mathematics is a somewhat difficult, but important
article about the contributions of the Arabs in the field of mathematics.
Within a century of Muhammad's conquest of Mecca, Islamic
armies conquered lands from northern Africa, southern Europe, through the
Middle East and east up to India. Within a century of that the Caliphate split
up into several parts. The eastern segment, under the Abbasid caliphs, became a
center of growth, of luxury, and of peace. In 766 the caliph al-Mansur founded
his capitol in Baghdad and the caliph Harun al-Rashid, established a library.
The stage was set for his successor, Al-Ma'mum.
In the 9 century Al-Ma'mum established Baghdad as the new
center of wisdom and learning. He establihed a research institute, the Bayt
al-Hikma (House of Wisdom), which would last more than 200 years. Al-Ma'mum was
responsible for a large scale translation project of as many ancient works as
could be found. Greek manuscripts were obtained through treaties. By the end of
the century, the major works of the Greeks had been translated. In addition,
they learned the mathematics of the Babylonnians and the Hindus.
What follows is a brief introduction to a few of the more
prominent Arab mathematicians, and a sample of their work
impression of Nasir al-Tusi on an Iranian stamp.
Al-Khwarizmi's main concern was with quadratic equations
possessing positive roots, which he noted can be encountered in one of three
standard forms. These equations involve three kinds of quantities: simple
numbers, the root (which is the unknown, x) and wealth, known as Mal in Arabic
and is the square of the root. The labels indicate the real world motivation
that often drove such enquiries within Muslim civilisation. Al-Khwarizmi then
proceeded to describe in detail the numerical procedures that solve particular
examples of equations drawn from one of the three standard types. The formula
that is recorded is nothing more than a verbal description of the standard
quadratic formula that we learnt at school. The distinguishing feature of
Al-Khwarizmi's work, and indeed of his successors, is the proof that is
provided for the validity of the numerical procedure using the axioms and
theorems of geometry. Thabit bin Al-Qurra extended Al-Khwarizmi's contributions
by demonstrating the validity of the formula for the unknown of general classes
of quadratic equations. He undertook this by first stating basic theorems of
geometry from Euclid; the various entities in the equations, including the
unknowns are related to the corresponding geometric quantities, namely line
segments and areas; finally using this geometric interpretation for the terms
of the equation, Al-Qurra was able to show the correspondence between the
geometric and algebraic solutions.
The full "arithmetisation of algebra" and
extension of the study of equations to include higher order unknowns, was
ushered in by Al-Karaji, who conducted his work in Baghdad around 1000 CE. It
was Al-Karaji's view that unknowns need not be limited to roots and their
squares, whether geometric magnitudes or absolute numbers. More generally,
unknowns could appear as cubes, x3, mal mal, x4, mal cube, x5, and so on. Thus
was he able to manipulate polynomial expressions, such as x4 + 4 x 3 – 6, employing
rules based on the ordinary arithmetic rules for adding, subtracting,
multiplying, dividing and extracting square roots. However, Al-Karaji did not
quite complete the arithmetisation of algebra; the matter had to wait 70 years
for another brilliant scholar, al-Samaw'al bin Yahya bin Yahuda al-Maghribi, to
add the finishing touches. The remaining step rested on fully incorporating
negative numbers into the theory. Although al-Karaji had managed to discover
rules such as a – (– b) = a + b, he hadn't quite encountered the related
identity, – a – (– b) = – (a + b). Such identities involving negative entities
are not as trivial as they seem, particularly when they must be developed or
discovered for the first time. As Berggren consoles:
"Students who have struggled with the law of signs may
find comfort in learning that at one time the discovery of these rules taxed
the ingenuity of the best mathematicians, and that the discovery of much of our
elementary (pre-calculus) mathematics was a matter of considerable labor and
many false starts".
A contemporary scholar, Ruth McNeill, reminisces on how such
rules led her to abandon mathematics:
"What did me in was the idea that a negative number
times a negative number comes out to a positive number. This seemed (and still
seems) inherently unlikely – counterintuitive, as mathematicians say. I
wrestled with the idea for what I imagine to be several weeks, trying to get a
sensible explanation from my teacher, my classmates, my parents, anybody."
This, then, makes al-Samaw'al's statement of the missing
relation all the more remarkable. The statement appears in his exotically
entitled work, Al-Bahir fi'l – Hasib (The Shining Book on Calculation), which
he wrote when he was only nineteen: " … if we subtract a deficient number
from a deficient number larger than it, there remains the difference [e.g. – 5
– (– 2) = – (5 – 2)], deficient; but in the other case there remains their
difference, excess. [e.g. – 2 – (– 5) = + (5 – 2)]."
Al-Samaw'al's personal life makes for interesting reading.
He was actually born into a Jewish family and was forced to complete the study
of the remaining volumes of Euclid's Elements on his own. This was on account
of not finding a sufficiently competent teacher of Mathematics in Baghdad at the
time. He proceeded to study, again by himself, the work of Al-Karaji, which he
then elaborated and extended. His conversion to Islam, according to his
autobiography, was inspired by a dream he had in 1163. He spent his life
traveling as a medical doctor, treating Princes on occasion, and died in
Maragha, northern Iran, around 1180. In total, Al-Samaw'al's encyclopedic
achievements spanning mathematics, astronomy, medicine and theology, fill
eighty-five works, only a few of which have survived. Along with the rules
relating to manipulating negative numbers described above, the law of exponents
and division of polynomials are all considered in one of Al-Samawa'al's
surviving mathematical studies, The Shining. What we would express today in
modern notation as x-3 x-4 = x-7, Al-Samaw'al records in the language of his
time as in this excerpt:
"Opposite [above] the order of part of cube is 3 and
opposite part of mal mal is 4. We add them to obtain 7 and opposite it is the
order of part of mal mal cube."
Such excursions in the world of exponents assisted
Al-Samaw'al as he applied his sharp mind to the problem of dividing one
polynomial by another. The details of the procedure need not concern us here;
it suffices to reproduce Berggren's summary:
"… the discovery of this procedure of long division,
which is in all its computation precisely our present-day one, is a fine
contribution to the history of mathematics, and it seems to be a joint
accomplishment of al-Karaji and al-Samaw'al."
Nasir al-Din al-Tusi was born in 1201 in the city of Tus. He
spent his childhood and early youth in Tus, and received his primary education
from his father. He learnt mathematics from a well-known scholar of the era,
Kamal al-Din Muhammad Hasib, and received his logarithm, logic, philosophy and
cognition tuition from Abul-?asan Bahmanyar ibn Marzuban ‘Ajami Adarbayijani
(d. 1067) who was an Azerbaijani scholar and also Ibn Sîna's student. We have
the impression that he was a passionate, freethinking researcher with an
expansive wisdom, wide imagination and a sharp memory even at a young age.
After completing his education, Nasir al-Din al-Tusi arrived
in Kuhistan at the invitation of Nasir Muhtasham, the Ismaili governor, and
gained a great deal of respect amongst the Ismailis, also influencing them with
his ideas. However, their relationship soured with time, and Nasir al-Din
al-Tusi was then kept under surveillance in the castle of Alamut under the
control of the Ismaili's for twenty-two years. There, despite his harsh living
conditions, he produced his most important works on astronomy, philosophy,
logic and related areas of science.
In 1256 when the Ismaili's were defeated by Hulagu, Nasir
al-Din al-Tusi regained his freedom and became advisor to the Moghol ruler. In
1258, he obtained permission from Hulagu to build the Maragha observatory and
began to make observations there after its completion in 1259. Nasir al-Din
al-Tusi remained in his position during the regency of Abaka Khan, Hulagu's
successor, and died in Bagdad in 1274 [2]. He was a great figure in the Islamic
scientific tradition and a key contributor to both political and intellectual
life during a century that witnessed enormous changes in the world.
3. The impact of Al-Tusi on the Ottoman world
Nasir al-Din al-Tusi was one of the most prolific authors of
the Islamic medieval period, writing in both Persian and Arabic, over 150 works
(excluding his poetry). He wrote on both religious and secular topics. He was a
well-recognised scholar in the Ottoman world, as well as other parts of the
Islamic world. The fact that al-Tusi held an important place in the Ottoman
scientific literature is well understood from the fact that his books were
introduced into the madrasas as textbooks and numerous copies were kept in many
Ottoman libraries [3].
Furthermore, his works were utilised and translated into
Turkish by many Ottoman scholars from the time of the formation of the Empire.
His works including annotations were copied and translated, and several works
based upon them were produced. In addition to Nasir al-Din al-Tusi's actual
written legacy, some observational tools that he had developed in the Maragha
Observatory were also been copied and revised by Taqi al-Din Rasid in Istanbul
in the late 16th century [4]. This shows that al-Tusi was not only influential
in the literature of the Ottoman world, but also in developing astronomical
devices.
In addition to commentaries and translations of al-Tusi's
works, direct copies of them were made, including copies of the so-called
"Middle-books" or Mutawassitat, a collection of various works
redacted by al-Tusi in astronomy, mechanics and music [5]. One such copy was
produced at the request of the Ottoman Sultan Muhammad II in 1477–1478 [6].
In short, it can be said that the source of works that influenced
the Ottoman astronomy and that comprised Ottoman astronomical literature are
the works of scholars who were members of the Maragha, the Samarkand and the
Egyptian astronomy-mathematic schools. Amongst these are the important works of
Nasir al-Din al-Tusi, the head of the Maragha School. Some of the works that we
will be discussing in this paper are Zij Ilhani, al-Tadhkirat al-Nasiriyya, Si
Fasl, Bist Bab and Tahrir al-Majisti.
3.1. Si Fasl dar Ma'rifat-i Taqwim
The title of this treatise, which was written initially in
Persian, namely Si Fasl dar Ma'rifat-i Taqwim (Thirty Chapters on the Knowledge
of the Calendar) show clearly its subject and purpose [7].
This is also known as Risala-i Si Fasl. As one can guess
from the title, this work is made up of thirty chapters and is one of the most
famous and widely known works of Nasir al-Din al-Tusi on calendar making. This
work was written in the State of Assassins. The treatise chapters concern the
following topics: 1) on literal numeration, 2-6) on calendars and eras
including Jalali calendar of Khayyam (1048–1131), 7-16) on the Sun, the Moon,
and the planets, 17-30) on astrological problems.
The book was translated into Turkish by Ahmed-i Dai of
Germiyan [8] (d. after 1421). It was used by Ottoman scholars in the madrasas
as a textbook on astronomy and especially on calendar making. The number of
annotations from both the pre and post Ottoman era and the relatively high
number of translations made during the Ottoman era indicates how commonly and
frequently it was used. Twenty-six copies of this book are being displayed in
various libraries throughout Turkey. Ibrahim Hakki of Erzurum also mentions
Tartib al-Ulum in his book Ma'rifatnama. These citations show how common this
work was at madrasas in the 18th century. Between 1649 and 1650, similarly,
Hajji Khalifa advised his students to read Si Fasl [9].
3.1.2. Commentaries on ‘Si Fasl' during the Ottoman Period
a. Sharhu Si Fasl (in Arabic), written by ‘Abd al-Wacid b.
Muhammad al-Kutahi (d. 1435); it was translated later on into Turkish by
Ahmed-i Raci [10].
b. Muvadhdhih al-Rusum fi ‘ilm al-Nujum (in Persian), with a
commentary by Dellakoglu (d. 1495) in 1478 and dedicated to Sultan Muhammad II
(1451-1481) [11].
c. Mukhtasar dar Ma'rifat Taqwim (in Persian), written by
Hizir-Shah al-Mantashavi (d. 1449) [12].
3.1.2. Turkish Translations of Si Fasl
A. Tarjama-i Si Fasl [13]: Translated by Ahmed-i Dai of
Germiyan [14]. A note in the introduction to the book shows that it was a
textbook in the Ottoman madrasas [15]. In the introduction, Ahmed-i Dai said
that he dedicated the translation to Sultan Celebi Muhammad [16]. There are two
different editions of this translation [17]. I. H. Ertaylan first published the
translation of the book with Turkish transliteration as Eskâl-i Nâsir-i Tûsî
Tercümesi (Istanbul 1952). Later on, it was published again by Muammer Dizer
and T. N. Gencan with Turkish transliteration, footnotes and explanations [18].
B. Tarjama-i Mukhtasar dar Ma'rifat-i Taqwim: A translation
of Nasir al-Din al-Tusi's book on calendar making. Since it has seven chapters,
it might be an abridged version of Si Fasl. It is the first book on calendar
making during the Ottomans period. The only copy of the book contains the year
1397 [19].
C. Tarjama-i Sharh-i Si Fasl [20]. The Turkish translation
of Abd al-Wacid Kutahi's (d. 1435) commentary on Si Fasl (Sharh Si Fasl). It
was translated by Ahmed-i Raci (c. 1621) with the encouragement of Grand Vizier
Sokullu Mehmed Pasha's son Grand Vizier Ibrahim Pasha (d. 1622) [21].
In the Ottoman world, al-Tusi's tables were also extensively
used for calendar making and other activities related to astronomy and
astrology. In the book Istikhraj Dustur by Osman Efendizade Abdullah Efendi (d.
1780) for instance, there are ru'yat al-ahilla's (crescents observation) tables
for the year 1754–55 according to al-Tusi's tables for Istanbul's longitude
[22].
3.2. Tahrir Kitab usul al-Handasa li-Uqlidis
This famous book is a very important teatise of the Arabic
Euclidean tradition of geometry. It is the recension (tahrir) in Arabic by
Al-Tusi of the Elements of Euclid. Known in general under the title Tahrir
Kitab usul al-Handasa li-Uqlidis (Recension of the Book "Elements of
Geometry" of Euclid), it had also the following title in some copies:
Tahrir Uqlidis fi ‘ilm al-Handasa (Recension or Exposition of Euclid on the
Science of Geometry") [23].
Euclid's' Elements (Kitab al-Usul) was extensively used and
commentaries made on it in the Islamic world. Among them Nasir al-Din al-Tusi's
commentary Tahrir Usul al-Handasa completed in 1248 is the most successful and
valuable work focussing on Euclidean geometry [24].
According to Seyyed Hossein Nasr, Nasir al-Din al-Tusi's
Tahrir and the commentaries of al-Sayyid al-Sharif al-Jurjani were used since
the 13th century as the main course book for geometry lessons among the madrasa
students in both the Islamic world and the Ottoman State [25].
Kawakib-i Sab'a reports that students were taught Euclid's'
Book ranking at istiksâ, after Sharhu Ashkâl al-Ta'sis ranking at iktisar.
Here, what is meant by "Euclid's' Book" is Tahrir Usul al-Handasa
[26].
In the geometry section of his De La Littérature des Turcs,
Abbé Toderini provides the following information on the Ottoman teaching of
geometry:
"Geometry falls under the group of Turkish studies. In
academies (madrasa), there are professors (mudarris) for teaching it [geometry]
to young people. The time period between mathematics and rhetoric classes is
allocated to this mathematical branch... This science is taught in a special
manner. I have been to the Valide Madrasa twice, during which time students had
gathered to listen to the geometry class. They used an Arabic translation of
Euclid. There are many versions as well as commentaries of this book. Nasir
al-Din et-Tusi's commentary, which is regarded as the best of these, has
already become popular thanks to the Medicis Publishing House. This copy
contains a copy of the Turkish license granted by Sultan Murad III (1574-1595)
in Istanbul in 1587 [27]. "He has granted permission for the sale of this
book without any tax or liability within the entire Ottoman territory..."
[28].
There are also other records which show that the Tahrir Usul
al-Handasa was used at Ottoman madrasas. For example Munajjimbashi Mustafa Zeki
al-Istanbuli (d. 1739) was tutored with this book in 1712 by La'lizade
‘Abdülbaki b. Muhammad b. Ibrâhim (d. 1746); Yanyali As'ad Efendi with Usul-i
Uqlidis by Müneccimek Muhammad Efendi; and Hasan al-Jabarti at his home (d.
1774) with Tahrir Uqlidis by Husam al-Din al-Hindi in 1731 [29].
3.2.2. Commentaries on Tahrir Usul al-Handasa
Hajji Khalifa reports that the Ottomans scholars Al-Sayyid
al-Sharif and Kadizade-i Rumi had written one commentary each on Tahrir Usul
al-Handasa, and that Kadizade's commentary went as far as the seventh treatise
[30].
During the Ottoman period, the first study on the Tahrir is
Ilhaku Abu Ishaq by Abu Ishaq Abdullah al-Kirmani (15th century). This work
meticulously annotates the first four treatises of the Tahrir [31].
Another study on the Tahrir is the Ta'lik of the chief
astronomer Munajjimbashi Darwish Ahmed Dede b. Lütfullah (d. 1702) titled
Tahrir al-Fawa'id (in Arabic). It is referred to as Ta'likat ‘ala Uqlidis
(Notes on Euclid) in some sources [32].
An additional work on the Tahrir is the Sharh Ba'd
al-Makalat al-Uklidisiyya (in Arabic) by Bedruddin Muhammad b. As'ad b. Ali b.
‘Osman b. Mustafa al-Yanyavi al-Islamboli (d. 1733), son of Yanyali As'ad
Efendi [33]. However, this work is not covered in the literature. Containing
some problems on Euclidian geometry, this book is one of the most important
works on Euclidian geometry produced during the Ottoman period [34].
3.3. Risala-i bist bab dar ma'rifet-i asturlab
This work of Nasir al-Din al-Tusi in the field of the
astrolabe is one of the books most used, studied and taught in Ottoman madrasas
[36]. It is titled Risala-i bist bab dar ma'rifet-i asturlab (in Persian), that
is Treatise in Twenty Chapters on the Knowledge of the Astrolabe) [37]. There
are fifty-two copies of this book in Turkish libraries. Erzurumlu Ibrahim Hakki
recommended this book to madrasa students by saying "regard the astrolabe
as one of the applied sciences / Fly with Bist Bab to watch the solar
system" in his Tartib-i Ulum. The book was taught by Hajji Khalifa many
times to students between 1649 and 1650.
3.3.1. Commentaries on Bist bab
a. Sharh-i bist bab dar ma'rifat-i asturlab (in Persian):
This commentary was written by Muhammad b. Haci b. Suleyman al-Bursavi (d. c.
1495) also known as Efezade, and presented to Sultan Bayezid II (1481-1512)
[38].
b. Sharh-i bist bab dar ma'rifat-i asturlab (in Persian):
Authored in Persian by al-Birjandi in 1494, this work was taught at madrasas.
There are around 30 copies of it [39].
3.3.2. Translations of Bist Bab
A. Tarjama-i bist bab (in Turkish): This was translated into
Turkish by an anonymous translator who explains in the introduction that the
translation was done for Ayaz Aga, one of the entourage of the sultan of the
time. This person is probably Ayaz Pasha, who served as Janissary Aga and Grand
Vizier in the time of Yavuz Sultan Selim and Suleiman the Magnificent [40].
B. Nuzhat al-Tullab fi ‘ilm al-asturlab (in Arabic):
Translated by Haydar b. ‘Abdurrahman al-Husayni al-Jazari (d. c. 1689) from
Persian into Arabic, there are currently forty three copies of this book [41].
C. Risala-i fi ma'rifet-i sihhat al-Asturlab (in Arabic):
The chapters on whether the astrolabe was built with accurately, and showing of
fixed stars on the orbit of the spider, it was translated in 1716 by an unknown
person [42].
Bist Bab was also partly translated. For example, Ibrahim b.
Halil al-Erzurumi al-Haddadi, also known as "Yekdest," translated
into Turkish the section on "Signs of Twenty Seven Stars" at the end
of Bist Bab [43].
3.4. Al-Tadhkira al-Nasiriyya fi ‘ilm al-hay'a
Nasir al-Din al-Tusi's Al-Tadhkira fi ‘ilm al-hay'a (Memoir
on the Science of Astronomy) [44] (in Arabic) is one of the most original and
influential Arabic works in astronomy. It is a text devoted to disclose the
general principles of astronomy for the general reader, whence its title as
Tadhkira (Memoir). The treatise described Ptolemaic concepts such as the
epicycle theory and introduced new planetary models. Al-Tadhkira is one of the
two books which the Samarkand school of mathematics/astronomy studied, read,
taught, discussed and commented on the most. It is placed at the heart within
the Islamic astronomical tradition. At the same time, it was also taught as a
textbook at Samarkand Madrasa [45].
Used in the Ottoman world as an astronomy textbook at the
madrasas, this book of al-Tusi consisted of four chapters. Having many
commentaries, the most famous of which in the Muslim world is that of
al-Birjandi. The book has kept its popularity until today. It too was taught at
Iranian madrasas. A commentary on Al-Tadhkira was produced on by its author
under the name Tavdhih Al-Tadhkira.
While Taskoprülüzade also places this work in the group of
compendia, Hajji Khalifa places it under the heading Al-Tadhkirat al-Nasiriyya
fi al-hay'a, explaining that it is a compendium containing issues and certain
findings of astronomy. Twenty copies are found in Turkish libraries.
3.4.1. Commentaries during the Ottoman Period
We learn from the commentaries that this work by Nasir
al-Din al-Tusi was respected as a textbook and taught at Ottoman madrasas:
a. Sharh Al-Tadhkira fi al-hay'a [46] (in Arabic): Fathullah
Shirwani (d. 1486) first wrote commentaries on the works of his mentor and then
penned some additional commentaries on the important theoretical work of Nasir
al-Din al-Tusi (d. 1273) on astronomical history, Al-Tadhkira fi ilm al-hay'a.
Making use of commentaries previously written by al-Sayyid al-Sharif al-Jurjani
and Nizam al-Din al-A'raj al-Nishaburi, Shirwani wrote this commentary
completed in 1475, to build on these previous works and to offer a complete
textbook to his students [47]. Some chapters of this book tell the reader about
the Ulugh Bey Madrasa and his own student years there. The 54-page appendix
following the first chapter is like an individual book on optics.
b. Sharh-i al-Tadhkira-i Haja Nasir-i Tusi (in Persian) was
authored by al-Birjandi in 1507 [48].
c. Sharh al-Tadhkira al-Nasiriyye fi al-hay'a (in Arabic):
Belongs to Kadizade Rumi [49].
3.5. Tansuq-nama-yi Ilhani
One of the books most widely used in mineralogy was
Tansugname-i Ilhani or Jawahir-nama (Book on Precious Stones) of Nasir al-Din
al-Tusi [50]. Al-Tusi wrote this book in Persian in Maragha and dedicated it to
Hulagu Han [51]. It was known and used in the Ottoman world from the earliest
period. Taskoprülüzade Ahmed Efendi pointed out the importance of this work
describing it as "the most useful and compact text on mineralogy"
[52]. Hajji Khalifa, who referred to it as Tansugname-i ilhani, said that
"it belongs to Nasir al-Din Muhammad b. Muhammad al-Tusi. It is a
compendium. It is organized into four treatises; on minerals, precious stones,
ores, and fragrant plants" [53].
This work was translated by Mustafa b. Seydi [54] (15th
century) for Beylerbeyi Karacabey in the time of Sultan Murad II (1421–1451)
[55] with the title Tarjama-i Tansugname-i Ilhani or Jawahirnama-i Sultan
Muradi [56]. On the cover of the translation, the title of the book is
Tarjama-i Kitab al-Jawahir al-Musamma bi-Tansikh-i Ilhani [57]. It is a
reorganized and abridged adaptation of Tansugname-i Ilhani. Mutarjim Mustafa
ibn Saydi removed the First, Third and Fourth treatises of the original text,
and only included the Second treatise which dwells on the characteristics of
mineral ores [58].
Another important characteristic of this work is that its
First Treatise contains information about ancient Chinese and Turkish medicine.
The book provides information about precious stones and their characteristics.
It consists of seven treatises each of which is called a Maqal [59]. While the
first six treatises deal with pearl, ruby, emerald, diamond and turquoise, the
seventh treatise provides organized information on musk, zebad, anbar, sandal,
ud (various perfumes) and camphor, and other eccentric and bizarre stones [60].
That this book was translated into Turkish in the time of
Sultan Murad II, and that it was included in the bibliography of the book
Yak'tat al-Mahazin fi Jawahir al-Ma'adin written by Yahya b. Muhammad
al-Gaffari in the name of Prince Korkut, suggests that this book was in demand
among the Ottomans [61].
3.6. Tahrir al-Majisti
The Almagest was Ptolemy's most influential work in the
Islamic world. The Tahrir al-Majisti (Exposition of the Almagest) [62] by
Al-Tusi (in Arabic) was also very popular in the Islamic world. The author
states he wrote the book due to the encouragement of Husam al-Din al-Hasan b.
Muhammad al-Sivasi, whom Al-Tusi calls sayf al-munadhirin (sword of the
debaters). There are twenty-two known copies of the work in Turkish libraries.
Nizam al-Din al-Nishaburi wrote a commentary of the work
with the title Ta'bir al-Tahrir. Later, Kadizade-i Rumi wrote a work entitled
Hashiya ‘ala Kitab al-Majasti (in Arabic) in which he explained certain
sections of the commentary of al-Nishaburi [63].
3.7. Kashf al-qina' ‘an asrar al-Shakl al-qatta'
This treatise Kashf al-qina' ‘an asrar al-Shakl al-qatta'
(Removal of the Veil from the Mysteries of the Secants Figure) bears sometimes
other titles, that is al-Risalat al-qatta' fi ‘ilm al-Handasa (Treatise on
Secants in the Science of Geometry) and Kitab al-shakl al-qatta' (The Book on
the Secant Figure). In all manuscripts, it is in Arabic.
Al-Tusi's work is the first systematic trigonometry text,
independent of astronomy in Muslim civilization. Hajji Khalifa proposes that
this book is related to the first figure in the first chapter of Menelaus of
Alexandria's (c. 70-140 CE) Kitâb al-Ukar's (Sphaerica). It was also first
written in Arabic and then translated into Persian by the author himself as a
five-chapter book [64]. The number of copies of the Kashf al-qina' in the
libraries indicates how commonly and frequently it was used through scholars
[65]. The French and the Turkish translations of the book in the Ottoman state
at the last quarter of 19th century and first quarter of the 20th century shows
that this book still very well-liked.
Alexandr Carathéodory published an Arabic edition of the
text, accompanied by a French translation [66]. The work was also translated
into Turkish by Celal Saygin (d. 1954) [67]. The printing of this book in the
Ottoman state at the end of the 19th century and translation of it in the
beginning of the 20th century shows how the Ottomans were still interested
al-Tusi's works. "The work in 5 books was written in the State of
Assassins for the great magister al-Muayyad ibn Husayn, in 1. On composed
ratios (in proposition 1 the notion of "quantity of a ratio" is
introduced, for ratio A/B it is quantity Q such that Q/1=A/B, therefore these
quantities are equivalent to our real numbers, and the quantity of a ratio
composed from two ratios is equal to product of quantities of quantities of
these ratios. 2. Theorem of plane figure of secants (plane complete
quadrilateral) and proof of the Menelaus theorem for this figure. 3.
Introduction to the theory of spherical figure of secants (spherical complete
quadrilateral). 4. Proof of the Menelaus theorem for spherical figure of
secants. 5. "Methods replacing figure of secants", that is, spherical
theorems of sines and tangents and solution of spherical triangles by three
known elements for all six cases, for triangles with three known angles – by
means of polar triangle" [68].
Tarjama-i al-Bah al-Shahiyya wa al-tarkibat al-Sultaniyya
Kitab al-bab al-bahiya fi al-tarakib al-sultaniya or
Bahnama-i Padishahi or al-Bah al-Shahiyya [69], written in Persian, is
attributed to al-Tusi [70]. A regimen for the ailing son of the sultan of
Qazan, it is divided into three parts of which the first two deal with
dietetics and health rules and the third with sexual intercourse. It was
translated from Persian into Turkish for the Ottoman Sultan Murad II by a
certain Musa b. Mas'ud [71], about whom nothing is known [72]. Consisting of
seventeen chapters, the work takes up subjects such as the temperament of
humans, aphrodisiacs, sorbets, pastes and healing drugs [73].
Al-'Ikd al-Yamani fi
Hall-i Zij Ilhani
It is a commentary in Arabic of Ibn al-Nakib [74] (d. 1563)
on Nasir al-Din al-Tusi's Zij Ilhani [75].
Muhammad ibn Muhammad ibn Hasan al-Tusi (born in 18 February
1201 in Tus, Khorasan – died on 26 June 1274 in Baghdad), better known as Nasir
al-Din al-Tusi, was a Muslim Persian scholar and prolific writer in different
fields of science and philosophy. He was an astronomer, mathematician,
physicist, philosopher, and theologian. Born in Tūs (northeast Iran), 17
February 1201 (11 Jumada al-Ula 597H) Died in Baghdad (Iraq), 25 June 1274 (18
Dhu'l-Hijjah 672H)
Muhammad ibn Muhammad ibn Hasan al-Tūsī (born in 18 February
1201 in Tūs, Khorasan – died on 26 June 1274 in Baghdad), better known as Nasīr
al-Dīn al-Tūsī, was a Muslim Persian scholar and prolific writer in different
fields of science and philosophy. He was an astronomer, mathematician,
physicist, philosopher, and theologian.
Al-Tūsī wrote over 150 works, in Arabic and Persian, that
dealt with mathematical sciences, philosophy, and the religious sciences (fiqh,
kalām, and Sufism). By his prolific oeuvre, the wide diffusion of his works and
their influence, he acquired the honorific titles of khwāja (distinguished
scholar and teacher), ustādh al-bashar (teacher of mankind), and al-mu'allim
al-thālith (the third teacher, after Aristotle and Al-Fārābī). In addition,
Al-Tūsī was the director of the Islamic major astronomical observatory of
Marāgha (northern Iran).
Al-Tūsī was born into a family of learned scholars. His
father and his uncles encouraged him to pursue the Islamic religious sciences
as well as the the rational sciences. He studied philosophy and mathematics in
his native town Tūs, but eventually traveled to Nīshāpūr (after 1213) in order
to continue his education in sciences, medicine, and philosophy. He studied the
works of Ibn Sīnā, who became an important formative influence. Al-Tūsī then
traveled to Iraq where his studies included legal theory; in Mosul (sometime
between 1223 and 1232), one of his teachers was Kamāl al-Dīn ibn Yūnus (died
1242), a legal scholar who was also renowned for his expertise in astronomy and
mathematics.
In the early 1230s, after completing his education, Tūsī
found patrons at the Ismā'īlī courts in eastern Iran. He eventually relocated
to Alamūt, the Ismā'īlī capital, and witnessed its fall to the Mongols in 1256.
Al-Tūsī then served under the Mongols as an advisor to their leader Hūlāgū,
becoming court astrologer as well as minister of religious endowments (awqāf).
In his new position, Al-Tūsī convinced Hūlāgū to found an astronomical
observatory and he oversaw the construction of this major scientific
institution and its instruments in Marāgha, the Mongol headquarters in
Azerbaijan, and he became its first director until his death in 1274. The
Marāgha Observatory also comprised a library and school. It was one of the most
ambitious scientific institutions established up to that time and may be
considered the first full-scale observatory. It attracted many famous and
talented scientists and students from the Islamic world and even from as far
away as China. The observatory lasted only about 50 years. However, even after its
activity stopped, the scientific legacy of Maragha observatory had
repercussions from China to Europe for centuries to come. Indeed, it is said
that Ulugh Beg's childhood memory of visiting the remnants of the Marāgha
Observatory as a youth contributed to his decision to build the Samarqand
Observatory. Mughal observatories in India, such as those built by Jai Singh in
the 18th century, clearly show the influence of these earlier observatories,
and it has been suggested that Tycho Brahe in late 16th century Europe might
have been influenced by them as well. In 1274 Tūsī left Marāgha with a group of
his students for Baghdad, where he died soon after.
Al-Tūsī's writings are both synthetic and original. His
recensions (tahārīr) of Greek and early Islamic scientific works, which
included his original commentaries, became the standard in a variety of
disciplines. These works included Euclid's Elements, Ptolemy's Almagest, and
the so called mutawassitāt (the "Intermediate Books" that were to be
studied between Euclid's Elements and Ptolemy's Almagest) with treatises by
Euclid, Theodosius, Hypsicles, Autolycus, Aristarchus, Archimedes, Menelaus,
Thābit ibn Qurra, and the Banū Mūsā. In mathematics, Al-Tūsī published a
sophisticated "proof" of Euclid's parallels postulate that was
important for the development of non-Euclidian geometry, and he treated
trigonometry as a discipline independent of astronomy, which was in many ways
similar to what was accomplished later in Europe by Johann Müller
(Regiomontanus). Other important and influential works include books on logic,
ethics, and a famous commentary on a philosophical work of Ibn Sīnā.
Nasīr al-Dīn al-Tūsī's major scientific writings in
astronomy, including Al-Tadhkira fī ‘ilm al-hay'a, in which he endeavoured to
reform Ptolemaic astronomy, had an enormous influence upon late medieval
Islamic astronomy as well as the work of early-modern European astronomers,
including Copernicus.
Al-Tūsī wrote several treatises on practical astronomy
(taqwīm), instruments, astrology, and cosmography/theoretical astronomy (‘ilm
al-hay'a). He also compiled a major astronomical handbook (in Persian) entitled
Zīj-i Īlkhānī for his Mongol patrons in Marāgha. Virtually all these works were
the subject of commentaries and supercommentaries, and many of his Persian
works were translated into Arabic. They were influential for later generations,
some still being used into the 20th century.
In planetary theory, Al-Tūsī sought to reform the Ptolemaic
system by correcting its inconsistencies, in particular its violations of the
fundamental principle of uniform circular motion for heavenly bodies. For this
purpose, he especially set forth an astronomical device (known among the
historians as the Tūsī-couple) that consisted of two circles, the smaller of
which was, internally, tangent to the other that was twice as large. The
smaller rotated twice as fast as the larger and in the opposite direction. Wit
this device, Al-Tūsī proved that a given point on the smaller sphere would
oscillate along a straight line. By incorporating this device into his lunar
and planetary models, Al-Tūsī reproduced Ptolemaic accuracy while preserving
uniform circular motion, a condition reconciling astronomy with the prevalent
natural philosophy. A second version of this device could produce
(approximately) oscillation on a great circle arc, allowing Al-Tūsī to deal
with irregularities in Ptolemy's latitude theories and lunar model.
Al-Tūsī disclosed these models in several of his works,
mainly in his famous Arabic treatise Al-Tadhkira fī ‘ilm al-hay'a (Memoir on
astronomy). His models were of major significance in the history of astronomy.
First, they produced models that adhered to both physical and mathematical
requirements; the two versions of the Tūsī couple, from the perspective of
mathematical astronomy, allowed for a separation of the effect of distance of
the planet from its speed (which had been tied together in the Ptolemaic
models). Al-Tūsī was thus able, for example, to circumvent Ptolemy's reliance
on a circular motion to produce a rectilinear, latitudinal effect. Second,
these new models were greatly instrumental for Al-Tusi's successors in Islamic
astronomy, such as his student Qutb al-Dīn al-Shīrāzī and Ibn al-Shātir (14th
century) as well as the work of early-modern European astronomers such as
Copernicus. Their influence crossed the borders of astronomy written in Arabic
or Persian and they are found in Sanskrit and Byzantine texts.
Al-Tūsī also influenced his astronomical and cosmological
successors with his discussion of the Earth's motion. Although he remained
committed to a geocentric universe, Al-Tūsī criticized Ptolemy's reliance on
observational proofs to demonstrate the Earth's stasis, noting that such proofs
were not decisive. Recent research has revealed a striking similarity between
Al-Tūsī's arguments and those of Copernicus.
Conclusion
Works of Nasir al-Din
al-Tusi have always attracted the interest of Ottoman scholars from the
earliest days until the last period. Some of his works were translated into
Turkish and various annotations or commentaries were written upon them. The
fact that some of his books were introduced in the madrasas as textbooks shows
the importance of his work. A large number of Nasir al-Din al-Tusi's works,
copies of his books and written annotations have lasted until today. It is
import to note that most of al-Tusi's works are being displayed in many
libraries of Turkey, especially Istanbul, and in many countries previously
governed by the Ottomans in order to understand the broader aspects of his
influence. This study examines al-Tusi's work on scientific fields such as
mathematics, astronomy, or mineralogy and demonstrates how important he was to
the Ottoman world. In addition, it is important to show how al-Tusi influenced
the Ottomans way of thinking by carefully considering his works on religion,
faith, philosophy and other social sciences. As a result of this study, Nasir
al-Din al-Tusi's contribution to European philosophy and science via the
Ottoman world can also be revealed.
The Influence of Nasir al-Din al-Tusi
on Ottoman Scientific Literature
The works of Nasir al-Din al-Tusi have always attracted the
interest of Ottoman scholars as early as the 14th century. Some of his works
were translated into Turkish and various annotations or commentaries were
written upon them. They were also introduced in the school curriculum as
textbooks, which testify to the wide scope of his impact on Ottoman
scholarship. Another aspect of his remarkable influence is represented by the
presence of very numerous manuscript copies of al-Tusi's works in many
libraries of Turkey, especially Istanbul, and in many countries previously
governed by the Ottomans. This article examines al-Tusi's work on scientific
fields practiced under the Ottomans such as mathematics, astronomy, scientific
instrumentation, and mineralogy and demonstrates how important he was to the
scholarship of the Ottoman world.
Nasir al-Din
Abu Ja'far Muhammad ibn Muhammad ibn al-hasan Muhammad ibn Muhammad b. Hasan
Abu Bakr al-Tusi (1201–1273/74)
Nasir al-Din Abu Ja'far Mu?ammad ibn Mu?ammad ibn al-?asan
Muhammad ibn Muhammad b. Hasan Abu Bakr al-Tusi (1201–1273/74) was a polymath
scholar of science and philosophy who wrote many books in diverse areas of
learning such as astronomy, mathematics, medicine, music, logic, physiology,
philosophy, literature, geography, theology and occult sciences. He also
founded and directed the famous Maragha observatory, one of the largest
astronomical observatories in the Islamic world [1].
2. Short biography
Nasir al-Din al-Tusi was born in 1201 in the city of Tus. He
spent his childhood and early youth in Tus, and received his primary education
from his father. He learnt mathematics from a well-known scholar of the era,
Kamal al-Din Muhammad Hasib, and received his logarithm, logic, philosophy and
cognition tuition from Abul-?asan Bahmanyar ibn Marzuban ‘Ajami Adarbayijani
(d. 1067) who was an Azerbaijani scholar and also Ibn Sîna's student. We have
the impression that he was a passionate, freethinking researcher with an
expansive wisdom, wide imagination and a sharp memory even at a young age.
After completing his education, Nasir al-Din al-Tusi arrived
in Kuhistan at the invitation of Nasir Muhtasham, the Ismaili governor, and
gained a great deal of respect amongst the Ismailis, also influencing them with
his ideas. However, their relationship soured with time, and Nasir al-Din
al-Tusi was then kept under surveillance in the castle of Alamut under the
control of the Ismaili's for twenty-two years. There, despite his harsh living
conditions, he produced his most important works on astronomy, philosophy,
logic and related areas of science.
In 1256 when the Ismaili's were defeated by Hulagu, Nasir
al-Din al-Tusi regained his freedom and became advisor to the Moghol ruler. In
1258, he obtained permission from Hulagu to build the Maragha observatory and
began to make observations there after its completion in 1259. Nasir al-Din
al-Tusi remained in his position during the regency of Abaka Khan, Hulagu's
successor, and died in Bagdad in 1274 [2]. He was a great figure in the Islamic
scientific tradition and a key contributor to both political and intellectual
life during a century that witnessed enormous changes in the world.
3. The impact of Al-Tusi on the Ottoman world
Nasir al-Din al-Tusi was one of the most prolific authors of
the Islamic medieval period, writing in both Persian and Arabic, over 150 works
(excluding his poetry). He wrote on both religious and secular topics. He was a
well-recognised scholar in the Ottoman world, as well as other parts of the
Islamic world. The fact that al-Tusi held an important place in the Ottoman
scientific literature is well understood from the fact that his books were
introduced into the madrasas as textbooks and numerous copies were kept in many
Ottoman libraries [3].
Furthermore, his works were utilised and translated into
Turkish by many Ottoman scholars from the time of the formation of the Empire.
His works including annotations were copied and translated, and several works based
upon them were produced. In addition to Nasir al-Din al-Tusi's actual written
legacy, some observational tools that he had developed in the Maragha
Observatory were also been copied and revised by Taqi al-Din Rasid in Istanbul
in the late 16th century [4]. This shows that al-Tusi was not only influential
in the literature of the Ottoman world, but also in developing astronomical
devices.
In addition to commentaries and translations of al-Tusi's
works, direct copies of them were made, including copies of the so-called
"Middle-books" or Mutawassitat, a collection of various works
redacted by al-Tusi in astronomy, mechanics and music [5]. One such copy was
produced at the request of the Ottoman Sultan Muhammad II in 1477–1478 [6].
In short, it can be said that the source of works that
influenced the Ottoman astronomy and that comprised Ottoman astronomical
literature are the works of scholars who were members of the Maragha, the
Samarkand and the Egyptian astronomy-mathematic schools. Amongst these are the important
works of Nasir al-Din al-Tusi, the head of the Maragha School. Some of the
works that we will be discussing in this paper are Zij Ilhani, al-Tadhkirat
al-Nasiriyya, Si Fasl, Bist Bab and Tahrir al-Majisti.
3.1. Si Fasl dar Ma'rifat-i Taqwim
The title of this treatise, which was written initially in
Persian, namely Si Fasl dar Ma'rifat-i Taqwim (Thirty Chapters on the Knowledge
of the Calendar) show clearly its subject and purpose [7].
This is also known as Risala-i Si Fasl. As one can guess
from the title, this work is made up of thirty chapters and is one of the most
famous and widely known works of Nasir al-Din al-Tusi on calendar making. This
work was written in the State of Assassins. The treatise chapters concern the
following topics: 1) on literal numeration, 2-6) on calendars and eras
including Jalali calendar of Khayyam (1048–1131), 7-16) on the Sun, the Moon,
and the planets, 17-30) on astrological problems.
The book was translated into Turkish by Ahmed-i Dai of
Germiyan [8] (d. after 1421). It was used by Ottoman scholars in the madrasas
as a textbook on astronomy and especially on calendar making. The number of
annotations from both the pre and post Ottoman era and the relatively high
number of translations made during the Ottoman era indicates how commonly and
frequently it was used. Twenty-six copies of this book are being displayed in
various libraries throughout Turkey. Ibrahim Hakki of Erzurum also mentions
Tartib al-Ulum in his book Ma'rifatnama. These citations show how common this work
was at madrasas in the 18th century. Between 1649 and 1650, similarly, Hajji
Khalifa advised his students to read Si Fasl [9].
3.1.2. Commentaries on ‘Si Fasl' during the Ottoman Period
a. Sharhu Si Fasl (in Arabic), written by ‘Abd al-Wacid b.
Muhammad al-Kutahi (d. 1435); it was translated later on into Turkish by
Ahmed-i Raci [10].
b. Muvadhdhih al-Rusum fi ‘ilm al-Nujum (in Persian), with a
commentary by Dellakoglu (d. 1495) in 1478 and dedicated to Sultan Muhammad II
(1451-1481) [11].
c. Mukhtasar dar Ma'rifat Taqwim (in Persian), written by
Hizir-Shah al-Mantashavi (d. 1449) [12].
3.1.2. Turkish Translations of Si Fasl
A. Tarjama-i Si Fasl [13]: Translated by Ahmed-i Dai of
Germiyan [14]. A note in the introduction to the book shows that it was a textbook
in the Ottoman madrasas [15]. In the introduction, Ahmed-i Dai said that he
dedicated the translation to Sultan Celebi Muhammad [16]. There are two
different editions of this translation [17]. I. H. Ertaylan first published the
translation of the book with Turkish transliteration as Eskâl-i Nâsir-i Tûsî
Tercümesi (Istanbul 1952). Later on, it was published again by Muammer Dizer
and T. N. Gencan with Turkish transliteration, footnotes and explanations [18].
B. Tarjama-i Mukhtasar dar Ma'rifat-i Taqwim: A translation
of Nasir al-Din al-Tusi's book on calendar making. Since it has seven chapters,
it might be an abridged version of Si Fasl. It is the first book on calendar
making during the Ottomans period. The only copy of the book contains the year 1397
[19].
C. Tarjama-i Sharh-i Si Fasl [20]. The Turkish translation
of Abd al-Wacid Kutahi's (d. 1435) commentary on Si Fasl (Sharh Si Fasl). It
was translated by Ahmed-i Raci (c. 1621) with the encouragement of Grand Vizier
Sokullu Mehmed Pasha's son Grand Vizier Ibrahim Pasha (d. 1622) [21].
In the Ottoman world, al-Tusi's tables were also extensively
used for calendar making and other activities related to astronomy and
astrology. In the book Istikhraj Dustur by Osman Efendizade Abdullah Efendi (d.
1780) for instance, there are ru'yat al-ahilla's (crescents observation) tables
for the year 1754–55 according to al-Tusi's tables for Istanbul's longitude
[22].
3.2. Tahrir Kitab usul al-Handasa li-Uqlidis
This famous book is a very important teatise of the Arabic
Euclidean tradition of geometry. It is the recension (tahrir) in Arabic by
Al-Tusi of the Elements of Euclid. Known in general under the title Tahrir
Kitab usul al-Handasa li-Uqlidis (Recension of the Book "Elements of
Geometry" of Euclid), it had also the following title in some copies:
Tahrir Uqlidis fi ‘ilm al-Handasa (Recension or Exposition of Euclid on the
Science of Geometry") [23].
Euclid's' Elements (Kitab al-Usul) was extensively used and
commentaries made on it in the Islamic world. Among them Nasir al-Din al-Tusi's
commentary Tahrir Usul al-Handasa completed in 1248 is the most successful and
valuable work focussing on Euclidean geometry [24].
According to Seyyed Hossein Nasr, Nasir al-Din al-Tusi's
Tahrir and the commentaries of al-Sayyid al-Sharif al-Jurjani were used since
the 13th century as the main course book for geometry lessons among the madrasa
students in both the Islamic world and the Ottoman State [25].
Kawakib-i Sab'a reports that students were taught Euclid's'
Book ranking at istiksâ, after Sharhu Ashkâl al-Ta'sis ranking at iktisar.
Here, what is meant by "Euclid's' Book" is Tahrir Usul al-Handasa
[26].
In the geometry section of his De La Littérature des Turcs,
Abbé Toderini provides the following information on the Ottoman teaching of
geometry:
"Geometry falls under the group of Turkish studies. In
academies (madrasa), there are professors (mudarris) for teaching it [geometry]
to young people. The time period between mathematics and rhetoric classes is
allocated to this mathematical branch... This science is taught in a special
manner. I have been to the Valide Madrasa twice, during which time students had
gathered to listen to the geometry class. They used an Arabic translation of
Euclid. There are many versions as well as commentaries of this book. Nasir
al-Din et-Tusi's commentary, which is regarded as the best of these, has
already become popular thanks to the Medicis Publishing House. This copy
contains a copy of the Turkish license granted by Sultan Murad III (1574-1595)
in Istanbul in 1587 [27]. "He has granted permission for the sale of this
book without any tax or liability within the entire Ottoman territory..."
[28].
There are also other records which show that the Tahrir Usul
al-Handasa was used at Ottoman madrasas. For example Munajjimbashi Mustafa Zeki
al-Istanbuli (d. 1739) was tutored with this book in 1712 by La'lizade
‘Abdülbaki b. Muhammad b. Ibrâhim (d. 1746); Yanyali As'ad Efendi with Usul-i
Uqlidis by Müneccimek Muhammad Efendi; and Hasan al-Jabarti at his home (d.
1774) with Tahrir Uqlidis by Husam al-Din al-Hindi in 1731 [29].
3.2.2. Commentaries on Tahrir Usul al-Handasa
Hajji Khalifa reports that the Ottomans scholars Al-Sayyid
al-Sharif and Kadizade-i Rumi had written one commentary each on Tahrir Usul
al-Handasa, and that Kadizade's commentary went as far as the seventh treatise
[30].
During the Ottoman period, the first study on the Tahrir is
Ilhaku Abu Ishaq by Abu Ishaq Abdullah al-Kirmani (15th century). This work
meticulously annotates the first four treatises of the Tahrir [31].
Another study on the Tahrir is the Ta'lik of the chief
astronomer Munajjimbashi Darwish Ahmed Dede b. Lütfullah (d. 1702) titled
Tahrir al-Fawa'id (in Arabic). It is referred to as Ta'likat ‘ala Uqlidis
(Notes on Euclid) in some sources [32].
An additional work on the Tahrir is the Sharh Ba'd
al-Makalat al-Uklidisiyya (in Arabic) by Bedruddin Muhammad b. As'ad b. Ali b.
‘Osman b. Mustafa al-Yanyavi al-Islamboli (d. 1733), son of Yanyali As'ad
Efendi [33]. However, this work is not covered in the literature. Containing
some problems on Euclidian geometry, this book is one of the most important
works on Euclidian geometry produced during the Ottoman period [34].
Figure 2: First pages of Bist bab dar ma'rifat-i
asturlab, Istanbul, Suleymaniye Library, Ayasofya, MS 2620.
3.3. Risala-i bist bab dar ma'rifet-i asturlab
This work of Nasir al-Din al-Tusi in the field of the
astrolabe is one of the books most used, studied and taught in Ottoman madrasas
[36]. It is titled Risala-i bist bab dar ma'rifet-i asturlab (in Persian), that
is Treatise in Twenty Chapters on the Knowledge of the Astrolabe) [37]. There
are fifty-two copies of this book in Turkish libraries. Erzurumlu Ibrahim Hakki
recommended this book to madrasa students by saying "regard the astrolabe
as one of the applied sciences / Fly with Bist Bab to watch the solar
system" in his Tartib-i Ulum. The book was taught by Hajji Khalifa many
times to students between 1649 and 1650.
3.3.1. Commentaries on Bist bab
a. Sharh-i bist bab dar ma'rifat-i asturlab (in Persian):
This commentary was written by Muhammad b. Haci b. Suleyman al-Bursavi (d. c.
1495) also known as Efezade, and presented to Sultan Bayezid II (1481-1512)
[38].
b. Sharh-i bist bab dar ma'rifat-i asturlab (in Persian):
Authored in Persian by al-Birjandi in 1494, this work was taught at madrasas.
There are around 30 copies of it [39].
3.3.2. Translations of Bist Bab
A. Tarjama-i bist bab (in Turkish): This was translated into
Turkish by an anonymous translator who explains in the introduction that the
translation was done for Ayaz Aga, one of the entourage of the sultan of the
time. This person is probably Ayaz Pasha, who served as Janissary Aga and Grand
Vizier in the time of Yavuz Sultan Selim and Suleiman the Magnificent [40].
B. Nuzhat al-Tullab fi ‘ilm al-asturlab (in Arabic):
Translated by Haydar b. ‘Abdurrahman al-Husayni al-Jazari (d. c. 1689) from
Persian into Arabic, there are currently forty three copies of this book [41].
C. Risala-i fi ma'rifet-i sihhat al-Asturlab (in Arabic):
The chapters on whether the astrolabe was built with accurately, and showing of
fixed stars on the orbit of the spider, it was translated in 1716 by an unknown
person [42].
Bist Bab was also partly translated. For example, Ibrahim b.
Halil al-Erzurumi al-Haddadi, also known as "Yekdest," translated
into Turkish the section on "Signs of Twenty Seven Stars" at the end
of Bist Bab [43].
Figure 3: First pages of Sharh-i bist bab dar
ma'rifet-i asturlab, Istanbul, Süleymaniye Library, Ayasofya, MS 2641.
3.4. Al-Tadhkira al-Nasiriyya fi ‘ilm al-hay'a
Nasir al-Din al-Tusi's Al-Tadhkira fi ‘ilm al-hay'a (Memoir
on the Science of Astronomy) [44] (in Arabic) is one of the most original and
influential Arabic works in astronomy. It is a text devoted to disclose the
general principles of astronomy for the general reader, whence its title as
Tadhkira (Memoir). The treatise described Ptolemaic concepts such as the
epicycle theory and introduced new planetary models. Al-Tadhkira is one of the
two books which the Samarkand school of mathematics/astronomy studied, read,
taught, discussed and commented on the most. It is placed at the heart within
the Islamic astronomical tradition. At the same time, it was also taught as a
textbook at Samarkand Madrasa [45].
Used in the Ottoman world as an astronomy textbook at the
madrasas, this book of al-Tusi consisted of four chapters. Having many
commentaries, the most famous of which in the Muslim world is that of
al-Birjandi. The book has kept its popularity until today. It too was taught at
Iranian madrasas. A commentary on Al-Tadhkira was produced on by its author
under the name Tavdhih Al-Tadhkira.
While Taskoprülüzade also places this work in the group of
compendia, Hajji Khalifa places it under the heading Al-Tadhkirat al-Nasiriyya
fi al-hay'a, explaining that it is a compendium containing issues and certain
findings of astronomy. Twenty copies are found in Turkish libraries.
3.4.1. Commentaries during the Ottoman Period
We learn from the commentaries that this work by Nasir
al-Din al-Tusi was respected as a textbook and taught at Ottoman madrasas:
a. Sharh Al-Tadhkira fi al-hay'a [46] (in Arabic): Fathullah
Shirwani (d. 1486) first wrote commentaries on the works of his mentor and then
penned some additional commentaries on the important theoretical work of Nasir
al-Din al-Tusi (d. 1273) on astronomical history, Al-Tadhkira fi ilm al-hay'a.
Making use of commentaries previously written by al-Sayyid al-Sharif al-Jurjani
and Nizam al-Din al-A'raj al-Nishaburi, Shirwani wrote this commentary
completed in 1475, to build on these previous works and to offer a complete
textbook to his students [47]. Some chapters of this book tell the reader about
the Ulugh Bey Madrasa and his own student years there. The 54-page appendix
following the first chapter is like an individual book on optics.
b. Sharh-i al-Tadhkira-i Haja Nasir-i Tusi (in Persian) was
authored by al-Birjandi in 1507 [48].
c. Sharh al-Tadhkira al-Nasiriyye fi al-hay'a (in Arabic):
Belongs to Kadizade Rumi [49].
3.5. Tansuq-nama-yi Ilhani
One of the books most widely used in mineralogy was
Tansugname-i Ilhani or Jawahir-nama (Book on Precious Stones) of Nasir al-Din
al-Tusi [50]. Al-Tusi wrote this book in Persian in Maragha and dedicated it to
Hulagu Han [51]. It was known and used in the Ottoman world from the earliest
period. Taskoprülüzade Ahmed Efendi pointed out the importance of this work
describing it as "the most useful and compact text on mineralogy"
[52]. Hajji Khalifa, who referred to it as Tansugname-i ilhani, said that
"it belongs to Nasir al-Din Muhammad b. Muhammad al-Tusi. It is a
compendium. It is organized into four treatises; on minerals, precious stones,
ores, and fragrant plants" [53].
This work was translated by Mustafa b. Seydi [54] (15th
century) for Beylerbeyi Karacabey in the time of Sultan Murad II (1421–1451)
[55] with the title Tarjama-i Tansugname-i Ilhani or Jawahirnama-i Sultan Muradi
[56]. On the cover of the translation, the title of the book is Tarjama-i Kitab
al-Jawahir al-Musamma bi-Tansikh-i Ilhani [57]. It is a reorganized and
abridged adaptation of Tansugname-i Ilhani. Mutarjim Mustafa ibn Saydi removed
the First, Third and Fourth treatises of the original text, and only included
the Second treatise which dwells on the characteristics of mineral ores [58].
Figure 4: The drawing of Nasir al-Din Tusi on a
recent Iranian stamp.
Another important characteristic of this work is that its
First Treatise contains information about ancient Chinese and Turkish medicine.
The book provides information about precious stones and their characteristics.
It consists of seven treatises each of which is called a Maqal [59]. While the
first six treatises deal with pearl, ruby, emerald, diamond and turquoise, the
seventh treatise provides organized information on musk, zebad, anbar, sandal,
ud (various perfumes) and camphor, and other eccentric and bizarre stones [60].
That this book was translated into Turkish in the time of
Sultan Murad II, and that it was included in the bibliography of the book
Yak'tat al-Mahazin fi Jawahir al-Ma'adin written by Yahya b. Muhammad
al-Gaffari in the name of Prince Korkut, suggests that this book was in demand
among the Ottomans [61].
3.6. Tahrir al-Majisti
The Almagest was Ptolemy's most influential work in the
Islamic world. The Tahrir al-Majisti (Exposition of the Almagest) [62] by
Al-Tusi (in Arabic) was also very popular in the Islamic world. The author
states he wrote the book due to the encouragement of Husam al-Din al-Hasan b.
Muhammad al-Sivasi, whom Al-Tusi calls sayf al-munadhirin (sword of the
debaters). There are twenty-two known copies of the work in Turkish libraries.
Nizam al-Din al-Nishaburi wrote a commentary of the work
with the title Ta'bir al-Tahrir. Later, Kadizade-i Rumi wrote a work entitled
Hashiya ‘ala Kitab al-Majasti (in Arabic) in which he explained certain
sections of the commentary of al-Nishaburi [63].
3.7. Kashf al-qina' ‘an asrar al-Shakl al-qatta'
This treatise Kashf al-qina' ‘an asrar al-Shakl al-qatta'
(Removal of the Veil from the Mysteries of the Secants Figure) bears sometimes
other titles, that is al-Risalat al-qatta' fi ‘ilm al-Handasa (Treatise on
Secants in the Science of Geometry) and Kitab al-shakl al-qatta' (The Book on
the Secant Figure). In all manuscripts, it is in Arabic.
Figure 5: The portrait of the Ottoman
Sultan Mehmet II (Muhammad II, 1451-1481).
Al-Tusi's work is the first systematic trigonometry text,
independent of astronomy in Muslim civilization. Hajji Khalifa proposes that
this book is related to the first figure in the first chapter of Menelaus of
Alexandria's (c. 70-140 CE) Kitâb al-Ukar's (Sphaerica). It was also first
written in Arabic and then translated into Persian by the author himself as a
five-chapter book [64]. The number of copies of the Kashf al-qina' in the
libraries indicates how commonly and frequently it was used through scholars
[65]. The French and the Turkish translations of the book in the Ottoman state
at the last quarter of 19th century and first quarter of the 20th century shows
that this book still very well-liked.
Alexandr Carathéodory published an Arabic edition of the
text, accompanied by a French translation [66]. The work was also translated
into Turkish by Celal Saygin (d. 1954) [67]. The printing of this book in the
Ottoman state at the end of the 19th century and translation of it in the
beginning of the 20th century shows how the Ottomans were still interested
al-Tusi's works. "The work in 5 books was written in the State of
Assassins for the great magister al-Muayyad ibn Husayn, in 1. On composed
ratios (in proposition 1 the notion of "quantity of a ratio" is
introduced, for ratio A/B it is quantity Q such that Q/1=A/B, therefore these
quantities are equivalent to our real numbers, and the quantity of a ratio
composed from two ratios is equal to product of quantities of quantities of
these ratios. 2. Theorem of plane figure of secants (plane complete
quadrilateral) and proof of the Menelaus theorem for this figure. 3.
Introduction to the theory of spherical figure of secants (spherical complete
quadrilateral). 4. Proof of the Menelaus theorem for spherical figure of
secants. 5. "Methods replacing figure of secants", that is, spherical
theorems of sines and tangents and solution of spherical triangles by three
known elements for all six cases, for triangles with three known angles – by
means of polar triangle" [68].
3.8. Tarjama-i al-Bah al-Shahiyya wa al-tarkibat
al-Sultaniyya
Kitab al-bab al-bahiya fi al-tarakib al-sultaniya or
Bahnama-i Padishahi or al-Bah al-Shahiyya [69], written in Persian, is
attributed to al-Tusi [70]. A regimen for the ailing son of the sultan of
Qazan, it is divided into three parts of which the first two deal with
dietetics and health rules and the third with sexual intercourse. It was
translated from Persian into Turkish for the Ottoman Sultan Murad II by a
certain Musa b. Mas'ud [71], about whom nothing is known [72]. Consisting of
seventeen chapters, the work takes up subjects such as the temperament of
humans, aphrodisiacs, sorbets, pastes and healing drugs [73].
3.9. Al-'Ikd al-Yamani fi Hall-i Zij Ilhani
It is a commentary in Arabic of Ibn al-Nakib [74] (d. 1563)
on Nasir al-Din al-Tusi's Zij Ilhani [75].
Muhammad ibn Muhammad ibn Hasan al-Tusi (born in 18 February
1201 in Tus, Khorasan – died on 26 June 1274 in Baghdad), better known as Nasir
al-Din al-Tusi, was a Muslim Persian scholar and prolific writer in different
fields of science and philosophy. He was an astronomer, mathematician,
physicist, philosopher, and theologian.
Born in Tūs (northeast Iran), 17 February 1201 (11 Jumada
al-Ula 597H)
Died in Baghdad (Iraq), 25 June 1274 (18 Dhu'l-Hijjah 672H)
Muhammad ibn Muhammad ibn Hasan al-Tūsī (born in 18 February
1201 in Tūs, Khorasan – died on 26 June 1274 in Baghdad), better known as Nasīr
al-Dīn al-Tūsī, was a Muslim Persian scholar and prolific writer in different
fields of science and philosophy. He was an astronomer, mathematician, physicist,
philosopher, and theologian.
Al-Tūsī wrote over 150 works, in Arabic and Persian, that
dealt with mathematical sciences, philosophy, and the religious sciences (fiqh,
kalām, and Sufism). By his prolific oeuvre, the wide diffusion of his works and
their influence, he acquired the honorific titles of khwāja (distinguished
scholar and teacher), ustādh al-bashar (teacher of mankind), and al-mu'allim
al-thālith (the third teacher, after Aristotle and Al-Fārābī). In addition,
Al-Tūsī was the director of the Islamic major astronomical observatory of
Marāgha (northern Iran).
Al-Tūsī was born into a family of learned scholars. His
father and his uncles encouraged him to pursue the Islamic religious sciences
as well as the the rational sciences. He studied philosophy and mathematics in
his native town Tūs, but eventually traveled to Nīshāpūr (after 1213) in order
to continue his education in sciences, medicine, and philosophy. He studied the
works of Ibn Sīnā, who became an important formative influence. Al-Tūsī then
traveled to Iraq where his studies included legal theory; in Mosul (sometime
between 1223 and 1232), one of his teachers was Kamāl al-Dīn ibn Yūnus (died
1242), a legal scholar who was also renowned for his expertise in astronomy and
mathematics.
In the early 1230s, after completing his education, Tūsī
found patrons at the Ismā'īlī courts in eastern Iran. He eventually relocated
to Alamūt, the Ismā'īlī capital, and witnessed its fall to the Mongols in 1256.
Al-Tūsī then served under the Mongols as an advisor to their leader Hūlāgū,
becoming court astrologer as well as minister of religious endowments (awqāf).
In his new position, Al-Tūsī convinced Hūlāgū to found an astronomical
observatory and he oversaw the construction of this major scientific institution
and its instruments in Marāgha, the Mongol headquarters in Azerbaijan, and he
became its first director until his death in 1274. The Marāgha Observatory also
comprised a library and school. It was one of the most ambitious scientific
institutions established up to that time and may be considered the first
full-scale observatory. It attracted many famous and talented scientists and
students from the Islamic world and even from as far away as China. The
observatory lasted only about 50 years. However, even after its activity
stopped, the scientific legacy of Maragha observatory had repercussions from
China to Europe for centuries to come. Indeed, it is said that Ulugh Beg's
childhood memory of visiting the remnants of the Marāgha Observatory as a youth
contributed to his decision to build the Samarqand Observatory. Mughal
observatories in India, such as those built by Jai Singh in the 18th century,
clearly show the influence of these earlier observatories, and it has been
suggested that Tycho Brahe in late 16th century Europe might have been
influenced by them as well. In 1274 Tūsī left Marāgha with a group of his
students for Baghdad, where he died soon after.
Al-Tūsī's writings are both synthetic and original. His
recensions (tahārīr) of Greek and early Islamic scientific works, which
included his original commentaries, became the standard in a variety of
disciplines. These works included Euclid's Elements, Ptolemy's Almagest, and
the so called mutawassitāt (the "Intermediate Books" that were to be
studied between Euclid's Elements and Ptolemy's Almagest) with treatises by
Euclid, Theodosius, Hypsicles, Autolycus, Aristarchus, Archimedes, Menelaus,
Thābit ibn Qurra, and the Banū Mūsā. In mathematics, Al-Tūsī published a
sophisticated "proof" of Euclid's parallels postulate that was
important for the development of non-Euclidian geometry, and he treated
trigonometry as a discipline independent of astronomy, which was in many ways
similar to what was accomplished later in Europe by Johann Müller (Regiomontanus).
Other important and influential works include books on logic, ethics, and a
famous commentary on a philosophical work of Ibn Sīnā.
Nasīr al-Dīn al-Tūsī's major scientific writings in
astronomy, including Al-Tadhkira fī ‘ilm al-hay'a, in which he endeavoured to
reform Ptolemaic astronomy, had an enormous influence upon late medieval
Islamic astronomy as well as the work of early-modern European astronomers,
including Copernicus.
Al-Tūsī wrote several treatises on practical astronomy
(taqwīm), instruments, astrology, and cosmography/theoretical astronomy (‘ilm
al-hay'a). He also compiled a major astronomical handbook (in Persian) entitled
Zīj-i Īlkhānī for his Mongol patrons in Marāgha. Virtually all these works were
the subject of commentaries and supercommentaries, and many of his Persian
works were translated into Arabic. They were influential for later generations,
some still being used into the 20th century.
In planetary theory, Al-Tūsī sought to reform the Ptolemaic
system by correcting its inconsistencies, in particular its violations of the
fundamental principle of uniform circular motion for heavenly bodies. For this
purpose, he especially set forth an astronomical device (known among the
historians as the Tūsī-couple) that consisted of two circles, the smaller of
which was, internally, tangent to the other that was twice as large. The
smaller rotated twice as fast as the larger and in the opposite direction. Wit
this device, Al-Tūsī proved that a given point on the smaller sphere would
oscillate along a straight line. By incorporating this device into his lunar
and planetary models, Al-Tūsī reproduced Ptolemaic accuracy while preserving
uniform circular motion, a condition reconciling astronomy with the prevalent
natural philosophy. A second version of this device could produce
(approximately) oscillation on a great circle arc, allowing Al-Tūsī to deal
with irregularities in Ptolemy's latitude theories and lunar model.
Al-Tūsī disclosed these models in several of his works,
mainly in his famous Arabic treatise Al-Tadhkira fī ‘ilm al-hay'a (Memoir on
astronomy). His models were of major significance in the history of astronomy.
First, they produced models that adhered to both physical and mathematical
requirements; the two versions of the Tūsī couple, from the perspective of
mathematical astronomy, allowed for a separation of the effect of distance of
the planet from its speed (which had been tied together in the Ptolemaic
models). Al-Tūsī was thus able, for example, to circumvent Ptolemy's reliance
on a circular motion to produce a rectilinear, latitudinal effect. Second,
these new models were greatly instrumental for Al-Tusi's successors in Islamic
astronomy, such as his student Qutb al-Dīn al-Shīrāzī and Ibn al-Shātir (14th
century) as well as the work of early-modern European astronomers such as
Copernicus. Their influence crossed the borders of astronomy written in Arabic
or Persian and they are found in Sanskrit and Byzantine texts.
Al-Tūsī also influenced his astronomical and cosmological successors
with his discussion of the Earth's motion. Although he remained committed to a
geocentric universe, Al-Tūsī criticized Ptolemy's reliance on observational
proofs to demonstrate the Earth's stasis, noting that such proofs were not
decisive. Recent research has revealed a striking similarity between Al-Tūsī's
arguments and those of Copernicus.
References
4. Conclusion
Works of Nasir al-Din al-Tusi have always attracted the
interest of Ottoman scholars from the earliest days until the last period. Some
of his works were translated into Turkish and various annotations or
commentaries were written upon them. The fact that some of his books were
introduced in the madrasas as textbooks shows the importance of his work. A
large number of Nasir al-Din al-Tusi's works, copies of his books and written
annotations have lasted until today. It is import to note that most of
al-Tusi's works are being displayed in many libraries of Turkey, especially
Istanbul, and in many countries previously governed by the Ottomans in order to
understand the broader aspects of his influence. This study examines al-Tusi's
work on scientific fields such as mathematics, astronomy, or mineralogy and
demonstrates how important he was to the Ottoman world. In addition, it is
important to show how al-Tusi influenced the Ottomans way of thinking by
carefully considering his works on religion, faith, philosophy and other social
sciences. As a result of this study, Nasir al-Din al-Tusi's contribution to
European philosophy and science via the Ottoman world can also be revealed.
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Badakhchani, S. J. (1998). Nasir al-Din al-Tusi.
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Bunyatov, Ziya. (1991). "Azerbaycan", Turkiye
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Izgi Cevat. (1997). Osmanli Medreselerinde Ilim,
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