Feb 172016


Today is the birthday (1201) of Khawaja Muhammad ibn Muhammad ibn Hasan Tūsī (Persian: محمد بن محمد بن الحسن طوسی‎‎), better known as Nasīr al-Dīn Tūsī (Persian: نصیر الدین طوسی‎)‎; or simply Tusi in the West, a Persian polymath and prolific writer – an architect, astronomer, biologist, chemist, mathematician, philosopher, physician, physicist, scientist, and theologian. The Muslim scholar Ibn Khaldoun (1332–1406) https://www.bookofdaystales.com/ibn-khaldoun/ considered Tusi to be the greatest of the later Persian scholars.

Tusi was born in the city of Tus in medieval Khorasan (in north-eastern Iran) and began his studies at an early age. In Hamadan and Tus he studied the Qur’an, Hadith, Shi’a jurisprudence, logic, philosophy, mathematics, medicine and astronomy.

He was apparently born into a Shī‘ah family and lost his father at a young age. Fulfilling the wish of his father, the young Tusi took learning and scholarship very seriously and travelled far and wide to attend the lectures of renowned scholars and acquire the 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. He met also Farid al-Din ‘Attar, the legendary Sufi master who was later killed by Mongol invaders and attended the lectures of Qutb al-Din al-Misri.


In Mosul he studied mathematics and astronomy with Kamal al-Din Yunus (d. 1242). Later on he corresponded with Sadr al-Din al-Qunawi, the son-in-law of Ibn al-‘Arabi, and it seems that mysticism, as propagated by Sufi masters of his time, was not appealing to his mind and once the occasion was suitable, he composed his own manual of philosophical Sufism in the form of a small booklet entitled Awsaf al-Ashraf “The Attributes of the Illustrious”.

As the armies of Genghis Khan swept his homeland, he was employed by the Ismailis and made his most important contributions in science during this time when he was moving from one stronghold to another. He was captured after the invasion of the Alamut castle by the Mongol forces.


Tusi wrote about 150 works, of which 25 are in Persian and the remaining are in Arabic,[12] and there is one treatise in Persian, Arabic and Turkish. These include:

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 Shia doctrines.

Talkhis Al Mohassal(summary of summaries).

During his stay in Nishapur, Tusi established a reputation as an exceptional scholar. “Tusi’s prose writing, which number over 150 works, represent one of the largest collections by a single Islamic author.

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.

Based on the observations in this for the time being most advanced observatory, Tusi made very accurate tables of planetary movements as depicted in his book Zij-i ilkhani (Ilkhanic Tables). This book contains astronomical tables for calculating the positions of the planets and the names of the stars. His model for the planetary system is believed to be the most advanced of his time, and was used extensively until the development of the heliocentric model in the time of Nicolaus Copernicus. Between Ptolemy and Copernicus, he is considered to be one of the most eminent astronomers of his time.


For his planetary models, he invented a geometrical technique called a Tusi-couple, which generates linear motion from the sum of two circular motions. He used this technique to replace Ptolemy’s problematic equant for many planets, but was unable to find a solution to Mercury’s motion, which was solved later by Ibn al-Shatir as well as Ali Qushji. The Tusi couple was later employed in Ibn al-Shatir’s geocentric model and Nicolaus Copernicus’ heliocentric model. He also calculated the value for the annual precession of the equinoxes and contributed to the construction and usage of some astronomical instruments including the astrolabe.

Ṭūsī criticized Ptolemy’s use of observational evidence to show that the Earth was at rest, noting that such proofs were not decisive. Although it doesn’t mean that he was a supporter of the motion of the earth, as he and his 16th-century commentator al-Bīrjandī, maintained that the earth’s immobility could be demonstrated, but only by physical principles found in natural philosophy. Tusi’s criticisms of Ptolemy were similar to the arguments later used by Copernicus in 1543 to defend the Earth’s rotation.

About the essence of the Milky Way, Ṭūsī in his Tadhkira writes: “The Milky Way, is made up of a very large number of small, tightly-clustered stars, which, on account of their concentration and smallness, seem to be cloudy patches. Because of this, it was likened to milk in color.” Three centuries later the proof of the Milky Way consisting of many stars came in 1610 when Galileo used a telescope to study the Milky Way and discovered that it is really composed of a huge number of faint stars.


In his Akhlaq-i-Nasri, Tusi put forward a basic theory for the evolution of species that has a few components that pre-echo Darwin. He begins his theory of evolution with the universe once consisting of equal and similar elements. According to Tusi, internal contradictions began appearing, and as a result, some substances began developing faster and differently from other substances. He then explains how the elements evolved into minerals, then plants, then animals, and then humans. Tusi then goes on to explain how hereditary variability was an important factor for biological evolution of living things:

The organisms that can gain the new features faster are more variable. As a result, they gain advantages over other creatures. . . . The bodies are changing as a result of the internal and external interactions.

Tusi then discusses how organisms are able to adapt to their environments:

Look at the world of animals and birds. They have all that is necessary for defense, protection and daily life, including strengths, courage and appropriate tools [organs]. Some of these organs are real weapons. For example, horns-spear, teeth and claws-knife and needle, feet and hoofs-cudgel. The thorns and needles of some animals are similar to arrows. Animals that have no other means of defense (as the gazelle and fox) protect themselves with the help of flight and cunning. Some of them, for example, bees, ants and some bird species, have united in communities in order to protect themselves and help each other.

Tusi next explains how humans evolved from animals:

Such humans [probably anthropoid apes] live in the Western Sudan and other distant corners of the world. They are close to animals by their habits, deeds and behavior. The human has features that distinguish him from other creatures, but he has other features that unite him with the animal world, vegetable kingdom or even with the inanimate bodies. Before [the creation of humans], all differences between organisms were of the natural origin. The next step will be associated with spiritual perfection, will, observation and knowledge. All these facts prove that the human being is placed on the middle step of the evolutionary stairway. According to his inherent nature, the human is related to the lower beings, and only with the help of his will can he reach the higher development level.

In chemistry and physics, Tusi stated a version of the law of conservation of mass. He wrote that a body of matter is able to change, but is not able to disappear:

A body of matter cannot disappear completely. It only changes its form, condition, composition, color and other properties and turns into a different complex or elementary matter.

Tusi was the first to write a work on trigonometry independently of astronomy. In his Treatise on the Quadrilateral, gave an extensive exposition of spherical trigonometry, distinct from astronomy. It was in these works that trigonometry achieved the status of an independent branch of pure mathematics distinct from astronomy, to which it had previously been linked.

In his On the Sector Figure, appears the famous law of sines for plane triangles.

a/sin A = b/sin B = c/sin C

He also stated the law of sines for spherical triangles, discovered the law of tangents for spherical triangles, and provided proofs for these laws.


In February 2013, Google celebrated his 812th birthday with a doodle, which was accessible in its websites with Arabic language calling him al-farsi (the Persian). Arils are the seeds, which act as a garnish.

Pomegranate soup, or āsh-e anār, is a Persian and Mesopotamian dish (āsh) made from pomegranate juice and seeds, yellow split peas, rice, spices, and vegetables. It likely has ancient roots. It is generally more flavorful if you can find pomegranate syrup, but the pure juice will do.


Pomegranate Soup


2 tbsp extra virgin olive oil
1 cup fresh parsley, chopped
¾ cup fresh cilantro, chopped (or mint)
1 cup fresh spinach, chopped
1 leek, washed and sliced thin
8 cups light stock
⅓ cup fresh lemon juice
½ cup basmati rice, uncooked
⅓ cup yellow split peas, soaked overnight
¼ cup pomegranate syrup
2 tbsp sugar
freshly ground black pepper
pomegranate arils to garnish


Heat the olive oil in a large, heavy stock pot on medium heat. Add the parsley, cilantro, spinach and leek, and sauté for 10 minutes to wilt. Do not allow them to take on color.

Add the stock and lemon juice and bring to a simmer. Add the rice and split peas. Cook on a low heat until the rice is done (about 30 minutes). The split peas will cook at about the same time.

Add the pomegranate syrup and sugar. Season to taste with salt and pepper and simmer for another 10 minutes.

Pour the soup into deep bowls and garnish with about 1 tablespoon of pomegranate arils per bowl.

Serve with flatbread.

Mar 222014


Today is the birthday (1394) of Mīrzā Muhammad Tāraghay bin Shāhrukh (Chagatai: میرزا محمد طارق بن شاہ رخ, Persian: میرزا محمد تراغای بن شاہ رخ‎‎) better known as Ulugh Beg (الغ‌ بیگ) a ruler in the Timurid dynasty in Central Asia as well as an astronomer, mathematician and sultan. His commonly used name, Ulugh Beg, is not a personal name, but rather a nickname, which can be loosely translated as “Great Ruler” or “Patriarch Ruler” and was the Turkic equivalent of Timur’s Perso-Arabic title Amīr-e Kabīr. Ulugh Beg was also notable for his work in astronomy-related mathematics, such as trigonometry and spherical geometry. He built the great Ulugh Beg Observatory in Samarkand between 1424 and 1429. It was considered by scholars to have been one of the finest observatories in the Islamic world at the time and the largest in Central Asia. He built the Ulugh Beg Madrasah (1417–1420) in Samarkand and Bukhara, transforming the cities into cultural centers of learning in Central Asia. He was also a mathematics genius of the 15th century — albeit his mental aptitude was perseverance rather than any unusual endowment of intellect. His observatory is situated in Samarkand which is in Uzbekistan.


He ruled Uzbekistan, Tajikistan, Turkmenistan, Kyrgyzstan, southern Kazakhstan and most of Afghanistan for almost half a century from 1411 to 1449. He was a grandson of the great conqueror, Timur (Tamerlane) (1336–1405), and the oldest son of Shah Rukh, both of whom came from the Turkic Barlas ethnic group of Transoxiana (now Uzbekistan). His mother was a noblewoman named Goharshad, from the Turkic aristocracy of Giyasitdin Tarhan. Ulugh Beg was born in Sultaniyeh in Persia during Timur’s invasion. As a child he traveled through a substantial part of the Middle East and India as his grandfather expanded his conquests in those areas. After Timur’s death, however, and the accession of Ulugh Beg’s father to much of the Timurid Empire, he settled in Samarkand, which had been Timur’s capital. After Shah Rukh moved the capital to Herat (in modern Afghanistan), sixteen-year-old Ulugh Beg became his governor in Samarkand in 1409. In 1411, he became the sovereign ruler of the whole Mavarannahr khanate.


The teenaged ruler set out to turn the city into an intellectual center for the empire. Between 1417 and 1420, he built a madrasah (“university” or “institute”) on Registan Square in Samarkand (currently in Uzbekistan), and he invited numerous Islamic astronomers and mathematicians to study there. The madrasah building still survives. Ulugh Beg’s most famous pupil in astronomy was Ali Qushchi (died in 1474). He was also famous in the fields of medicine and poetry. He used to debate with other poets, regarding a range of contemporary issues. He liked to debate in a poetic style, called “Bahribayt” among local poets.

Ulugh Beg proposed that a mixture of alcohol with garlic, could help treat conditions like diarrhea, headache, stomach ache, and intestinal illnesses. He also offered advice for newly married couples, suggesting recipes containing nuts, dried apricot, dried grape etc. were useful in increasing a man’s virility. Fortunately his astronomy and mathematics were stronger than his medical skills.


His own particular interests concentrated on astronomy, and, in 1428, he built an enormous observatory, called the Gurkhani Zij, similar to Tycho Brahe’s later Uraniborg as well as Taqi al-Din’s observatory in Istanbul. Lacking telescopes to work with, he increased his accuracy by increasing the length of his sextant; the so-called Fakhri sextant had a radius of about 36 meters (118 feet) and the optical separability of 180″ (seconds of arc).

Using it, he compiled the 1437 Zij-i-Sultani of 994 stars, generally considered the greatest star catalog between those of Ptolemy and Brahe, a work that stands alongside Abd al-Rahman al-Sufi’s Book of Fixed Stars. The serious errors which he found in previous Arabian star catalogs (many of which had simply updated Ptolemy’s work, adding the effect of precession to the longitudes) induced him to redetermine the positions of 992 fixed stars, to which he added 27 stars from Abd al-Rahman al-Sufi’s catalog  Book of Fixed Stars from the year 964, which were too far south for observation from Samarkand. This catalog, one of the most significant of the Middle Ages, was first edited by Thomas Hyde at Oxford in 1665 under the title Tabulae longitudinis et latitudinis stellarum fixarum ex observatione Ulugbeighi and reprinted in 1767 by G. Sharpe. More recent editions are those by Francis Baily in 1843 in vol. xiii of the Memoirs of the Royal Astronomical Society and by Edward Ball Knobel in Ulugh Beg’s Catalogue of Stars, Revised from all Persian Manuscripts Existing in Great Britain, with a Vocabulary of Persian and Arabic Words (1917).

In 1437, Ulugh Beg determined the length of the sidereal year as 365.2570370…d = 365d 6h 10m 8s (an error of +58 seconds). For his measurements he used a 50 m high gnomon (shadow casting rod as on a sundial). This value was improved by 28 seconds in 1525 by Nicolaus Copernicus, who appealed to the estimation of Thabit ibn Qurra (826–901), which had an error of +2 seconds. However, Beg later measured another more precise value as 365d 5h 49m 15s, which has an error of +25 seconds, making it more accurate than Copernicus’ estimate which had an error of +30 seconds. Beg also determined the Earth’s axial tilt as 23.52 degrees, which remained the most accurate measurement for hundreds of years. It was more accurate than later measurements by Copernicus and Tycho Brahe.

In mathematics, Ulugh Beg wrote accurate trigonometric tables of sine and tangent values correct to at least eight decimal places. The trigonometric results include tables of sines and tangents given at 1° intervals. These tables display a high degree of accuracy, being correct to at least 8 decimal places. The calculation is built on an accurate determination of sin 1° which Ulugh Beg solved by showing it to be the solution of a cubic equation which he then solved by numerical methods. He obtained:

sin 1° = 0.017452406437283571

The correct approximation is:

sin 1° = 0.017452406437283512820

which shows the remarkable accuracy which Ulugh Beg achieved. Not a brilliant mathematician, but a dogged one.

Ulugh Beg’s scientific expertise was not matched by his skills in leadership. When he heard of the death of his father Shahrukh Mirza, Ulugh Beg went to Balkh, where he heard that his nephew Ala-ud-Daulah Mirza bin Baysonqor, son of Ulugh’s brother Baysonqor, had claimed the emirship of the Timurid Empire in Herat. Consequently Ulugh Beg marched against his nephew and met him in battle at Murghab. Having won this battle, Ulugh Beg advanced toward Herat and massacred its people in 1448. But Ala-ud-Daulah’s brother Mirza Abul-Qasim Babur bin Baysonqor came to his aid, defeating Ulugh Beg. Ulugh Beg retreated to Balkh, where he found that its governor, his oldest son Abdal-Latif Mirza, had rebelled against him. Another civil war ensued.


Within two years, he was beheaded by the order of his own eldest son while on his way to Mecca. Eventually, his reputation was rehabilitated by his nephew, Abdallah Mirza (1450–1451), who placed Ulugh Beg’s remains in the mausoleum of Timur in Samarkand, where they were found by archeologists in 1941. It was discovered that Ulugh Beg had been buried in his clothes which is known to indicate that he was considered a martyr. The injuries inflicted on him were evident when his body was examined :

… the third cervical vertebra was severed by a sharp instrument in such a way that the main portion of the body and an arc of that vertebra were cut cleanly; the blow, struck from the left, also cut through the right corner of the lower jaw and its lower edge.

Here is a classic soup from Yazd, now in Iran but in the Timurid Empire when Ulugh Beg ruled.  It is quite complex in flavor, but not awfully difficult to make.  The dill and beets are a common taste of the region.  The dumplings and yoghurt are essential for me to cut the richness of the soup.

© Shoorba-ye Yazdi (Lentil and Beet Soup with Pasta Dumplings)

Slice a medium onion and sauté in a little oil until golden.


Add ½ teaspoon of turmeric and sauté for a minute or two more.


Put the onions in a soup pot with 1 cup of lentils and 1 cup of diced beet.


Add 5 cups of chicken stock, bring to a boil and simmer until the lentils are soft (1 to 2 hours).


Add ½ cup of chopped greens (beet tops if available, otherwise chard or spinach) . . .


. . . and a handful of chopped dill.  Continue to simmer while you make the dumplings.


Place ½ cup of flour in a bowl.


Slowly add water until you have a soft dough.


Knead on a floured board for 5 minutes.


Tear into flat disks.


Add the dumplings to the soup and cook for 8 to 10 minutes, or until al dente.


Add 2 tablespoons of vinegar.


Serve hot in a deep bowl with a dollop of plain yoghurt or sour cream. It can also be served cold.