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History of Islamic Science 7
Based on the book
Introduction to the History of Scienceby George Sarton
(provided with photos and portraits)
Edited and prepared by Prof. Hamed A. Ead

These pages are edited by Prof. Hamed Abdel-reheem Ead, Professor of Chemistry at the Faculty of Science -University of Cairo, Giza, Egypt and director of the Science Heritage Center
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The Time of Omar Khayyam
(Second Half Of Eleventh Century)

The most original creations of this time were made in the field of mathematics by Muslims, and the most original genius among those to whom we owe these creations was the Persian Omar Khayyam. It is thus very appropriate to call this time the Time of Omar Khayyam, as Omar is already very well known to a large number of readers. It is probable that his name is more familiar to them than that of any other Muslim scientist. It will thus be relatively easy to remember the title, and I trust that this remembrance will reach to some extent the contents of the following pages. The time of Omar Khayyam was the end of the golden age of Muslim science.

A new Muslim sect, that of the Assassins, an off-shoot of the Ismailiya movement, originated in Cairo about 1080.
They took possession of the fortress of Alamut, which remained their main stronghold for a century and a half. Alamut seems to have been also a center of learning.
The Muslim philosopher who has obtained the largest following in the West, in fact the only one who has become at all popular, is the persian poet and sufi Omar Khayyam. On the other hand, one of Omar's contemporaries, al-Ghazzali, was the greatest theologian of Islam. He might be compared to Thomas Aquinas, to whom he was in many ways superior. Al-Ghazzali was also a Persian and spent part of his life in Omar's native place, Nishabur. While Omar Khayyam is the most popular fingure of mediaeval times, al-Ghazzali is probably the noblest.

Muslim Mathematics and Astronomy

Important astronomical work was done at Cordova. Ibn Said, aided by other Muslim and Jewish astronomers, made a number of observations. These observations were used by al-Zarqaili (Arzachel), for the compilation of new tables, the so-called Toledan tables, which obtained considerable authority in western Europe. Al-Zarqaili invented a new kind of astrolabe and proved the movement of the solar apogee; unfortunately, he confirmed the erroneous theory of the "trepidation" of the equinoxes. His tables were preceded, as usual, by an elaborate trigonometrical introduction.
The philosopher al-Ghazzali wrote a treatise on the motion and nature of stars and an astronomical summary; he had some knowledge of magic squares. The Bagdadite Muhammad ibn Àbd al-Baqí wrote a commentary on the tenth book of Euclid.
The activity of Muslim geographers, which had been so intense during the ninth and tenth centuries, abated during the present century. For the second half of this century two men will be recorded, one in the West and the other in the East. The western one, al-Bakri, is of special importance, become the road-book which the compiled in the traditional manner is the oldest one of its kind due to a Spaniard. He also compiled a dictionary of ancient (i.e., Arabian) geography. The Eastern one is also a very arresting personality. Nasir-I-Khusraw was an Ismaili missionary who, starting from Egypt, traveled extensively in the Near East and as far east as Persia. He wrote in Persia an account of his travels, which is equally valuable from the geographical and from the historical point of view.
The contributions of Islam may seem small, but they were still of a very high quality.
In spite of Anselm, Psellos, and Constantine, in spite of the Chanson de Roland, in spite of Alfasi, Rashi, and Nathan, Islam was still at the vanguard of humanity. There was nowhere else in the world, in those days, a philosopher who could at all compare with al-Ghazzali, neither an astronomer like al-Zarqali, neither a mathematician like Omar Khayyam. These men were to towering far above their contemporaries.
If we proceed to examine more carefully the intellectual condition of Islam, we discover, in the first place, that some of the most important contributions were due to Persians; this was not novelty, but what is more starting, they were written in Persian.
Al-Ghazzali was the only Persian who wrote in Arabic; al-Hasan ibn al-Sabbah, Omar Khayyam, Nasir-I-Khusraw, Zarrin Dast, Nidham al-Mulk, and Asadi wrote in Persian.
The city of the caliphs gave us still a number of scientists but none of great distinction - Muhammad ibn Àbd al-Baqí, Ibn Jazla (of Christian origin), Sa'íd ibn hibat Allah, al-Khatíb al-Baghdadí, and al-Mawardí. The only center of intellectual progress in Islam was Spain, but the heyday of Cordova was already over. Indeed, of the seven scientists and scholars who make us think of the Muslim Spain of those days with gratitude, only one can be connected with Cordova, the geographer al-Bakrí.
The greatest of them all, al-Zarqali, flourished in Toledo, and so did the original historian Ibn Sa'íd. Yusuf al-Mutamin lived in Saragossa; Abu 'Umar ibn Hajjaj in Seville. Ibn Sída, was born in Murcia and died in Denia.
But the development of astronomy by al-Zarqal and of algebra by Omar Khayyam were definite steps forward.
A great orientalist went so far as to say : "The fourth century is the turning-point in the history of the spirit of Islam".



In Latin : Arzachel. Abu Ishaq Ibrahim ibn Yahya al-Naqqash, the engraver. Better known as Ibn al-Zarqali. From Cordova, lived from c.1029 to c.1080. Astronomer. The best observer of his time (observations dated 1061, 1080).
He invented an improved astrolabe called safiham (saphaea Arzachelis); his description of it was translated into Latin, Hebrew, and many vernaculars. He was the first to prove explicitly the motion of the solar apogee with reference to the stars; according to his measurements it amounted to 12.04" per year (the real value being 11.8").
On the other hand, comparing his observation of the obliquity of the ecliptic with previous ones, he concluded that it oscillated between 23o 33' and 23o 53', thus reenforcing the erroneous belief in the "trepidation" of the equinoxes. He edited the so-called Toledan Tables, planetary tables based upon the observations made by him and probably other Muslim and Jewish astronomers in Toledo (notably Ibn Sa'íd).
These tables were translated into Latin by Gherardo Cremonese and enjoyed much popularity. The trigonometrical introduction (Canones sive regulae tabularum astronomiae) was al- Zarqali's own work; it explains the construction of the trigonometrical tables.


Of the tribe of the Banu Hud; king of Saragossa from 1081 to 1085. His father, Ahmed al-Muqtadir Billah, king from 1046 to 1081, was also a student and a patron of students. Hispano-Muslim mathematician and patron of science.
He wrote a mathematical treatise, Istikmal (Bringing to perfection), of which it was said that it should be studied together with Euclid, the Almagest, and the "middle books."p
No copy of Yusuf's treatise is known; it is strange that a work believed to be so important and written by a king should be lost.
Stanley Lane Poole: Mohammedan Dynasties (26,1893)
H.Suter: Mathematiker (108,1900).


Abu-l-Fath 'Umar ibn Ibrahím al-khayyamí - the tentmaker - Ghiyath al-dín. Born in or near Níshabur c. 1038 to 1048, died there in 1123-24.
Persian mathematician, astronomer, and poet. One of the greatest mathematicians of mediaeval times. His Algebra contains geometric and algebraic solutions of equations of the second degree; an admirable classification of equations, including the cubic; a systematic attempt to solve them all, and partial geometric solutions of most of them (he did not consider negative roots and his failure to use both branches or halves of a conic caused him to miss sometimes one of the positive roots). His classification of equations is very different from our own; it is based on the complexity of the equations (the number of different terms which they include).
Of course the higher the degree of an equation the more different terms, or combinations of terms, it can contain. Thus Omar recognizes 13 different forms of cubic equation. (The modern classification based primarily upon the degree dates only from the end of the sixteenth and the beginning of the seventeenth century).
Binomial development when the exponent is a positive integer. Study of the postulates and generalities of Euclid.
In 1074-75 the saljuq sultan Malikshah, Jalal al-dín, called him to the new observatory of Ray (or Níshabur, or Isfahan?) to reform the old Persian calendar:
(30x12)d.+5d.=365 d. The latter had been temporarily replaced by the Muslim calendar after the conquest. Omar's calendar was called al-ta'rikh al-Jalal.
Its era was the 10th Ramadan 471=16 March 1079. There are many interpretations of Omar's reform and to each corresponds a certain degree of accuracy, but at any rate, Omar's calendar was very accurate, probably more so than the Gregorian calendar.
The correct interpretation is probably one of the three following, the second being the most probable of them. I quote for each, the authority, then the gist of the change, and finally the resulting error:
According to al-Shirazi (d.1449), 15 intercalary days in 62 years; error, 1 day in about 3,770 years.
Moden interpretation, 8 intercalary days in 33 years; error, 1 day in about 5,000 years.
(The Gregorian calendar leads to an error of 1 day in 3,330 years).
Methods for the determination of specific gravity.
It is impossible not to mention the Ruba'iyat (quatrains) of Omar Khayyam, which have become, especially since 159 (when Edward Fitzgerald published the first instalment of his English paraphrase), one of the most popular classics of the world literature. Omar Khayyam was probably not a sufi, but rather an agnostic.
Comparisons of his thought with that of Lucretius and that of Voltaire are suggestive but indaequate.


Abu Bakr(?) Muhammad ibn 'Abd al-Baghdadi. Flourished c. 1100.
Possibly the author of a commentary on the tenth book of Euclid, which was very popular because of its numerical applications. It is entitled "Liber judei super decimum Euclidis" in the translation by Gherardo Cremonese.



Abu 'ali Yahya ibn Isa Ibn Jazla. Latin forms: Bengesla, Buhahylyha, Byngezla, etc.
Flourished in Bagdad, died in 1100. Christian physician, who embraced Islam in 1074. His most important work is a medical synopsis, wherein 44 tables of two pages each contain the description and outline the treatment of 352 diseases (8 in each table); it was probably modeled upon similar work of Ibn Butlan (q .v; first half of eleventh century) and is called "Tables of the Bodies with regard to their constitutions" (Taqwim al-abdan fi tadbir al-insa; dispositio corporum de constitutions hominis). He wrote for al-Muqtadi (caliph from 1075 to 1094) an alphabetical list of simple and compound medicines called "The Pathway of Explanation as to that which Man Uses" (Minhaj al-bayan fi ma yasta 'miluhu al-insan; methodica dispositio eorum, quibus homo uti solet).


Abu-I-Hassan Sa'id ibn Hibat Allah ibn al-Hasan. Flourished in Bagded under al-Muqtadi, caliph from 1075 to 1094, died in 1101-2. Physician and philosopher.
Author of a synopsis of medicine, Al-mughni fi tadbir al-amrad wa ma 'rifat al-'ilal wal-a'rad (Sufficiens de cura morborum et eognitione causarum et symptomarum) and of a treatise on physiology and psychology called "Discourse on the creation of Man", Maqala fi khalq al-insan (De constitutione hominis), dealing with such subjects as reproduction, gestation, parturition, growth, decay, survival of the soul, etc.


Abu Ruh Muhammad ibn Mansur ibn abi 'Abdallah ibn Mansur al-Jamani (or al-Jurjani). Zarrin Dast means the Golden Hand, a good name for an eye surgeon.
Flourished under the Saljuq sultan Abu-l-Fath Malikshah ibn Muhammad, ruling from 1072-73 to 1092-93. Persian oculist. He completed in 1087-88, a very comprehensive and very remarkable treatise on ophthalmology entitled "The Light of the Eyes" (Nur al-ayun) (in Persian).
Hirschberg: Geschichte der Augenheilkunde bei den Arabern (57 sq., Leipzig, 1905).
Adolf Fonahn: Quellenkunde der persischen Medizin (38-41, 1910. Includes summary of the treatise, based upon Hirschberg).