The ninth century was essentially a Muslim century. To be sure, intellectual work did not cease in other centuries; but the activity of the Muslim scholars and men of science was overwhelmingly superior. They were the real standard-bearers of civilization in those days. Their activity was superior in almost every respect. To consider only the first half of the century, the leading men of science, al-Kindi, the sons of Musa, Al-Khwarzmi, al-Farghani, were all Muslims; Ibn Masawaih, it is true, was a christian, but he wrote in Arabic.
Cultural Background
The seventh Abbasid caliph, al-Ma'mun (813-833), was even a greater patron of letters and science than Harun al-Rashid. He founded a scientific academy in Bagdad, tried to collect as many Greek manuscripts as possible, and ordered their translation; he encouraged scholars from all kinds, and an enormous amount of scientific work was done under his patronage.
al-Ma'mun
'Abdallah al-Ma'mun. Born in Baghdad in 786,
died near Tarsus in 833. The seventh and greatest 'Abbasid caliph (813-833).
His mother and wife were Persians, which explains his Persian and
'Alid proclivities. He was an ardent Mu'tazil, tried to enforce his views
by means of violence. He wrote four long letters to explain the Qur'an
was created, and he cruelly punished those who dared entertain different
views (e.g., Ibn Hannibal). He thus combined in a remarkable way free thought
and intolerance. While persecuting those who objected to Mu'tazilism,
Jews and Christians were very welcome at his court. He was even a greater
patron of letters and science than Harun al-Rashid. He took considerable
pains to obtain Greek manuscripts and even sent a mission to the Byzantine
Emperor Leon the Armenian (8l3 to 890) for that purpose. He ordered the
translation of these manuscripts. He organized at Baghdad a sort of scientific
academy called the House of Wisdom (Bayt al-hilkma), which included a library
and an observatory. This was the most ambitious undertaking of its
kind since the foundation of the Alexandrian Museum (q. v. first half of
third century B. C.). He built another observatory on the plain of Tadmor
(Palmyra). The inclination of the ecliptic was found by his astronomers
to equal 23o 33' and tables of the planetary motions were constructed.
He ordered two degree-measurements to be made to determine the size of
the earth one of them near Tadmor (a degree = 6,500 miles) hence circumference
of the earth = 20,400 miles; diameter=6,500 miles). A large map of
the world was drawn for him. He encouraged philosophers, philologists,
traditionalists, and other jurists mathematicians, physicians, astrologers
and alchemists.
Fihrist (116, 24.3 and passim). Gustav
Weil: Gesehichte (ler Chalifen (vol.2 198-994). J. T. Remaud: Geographie
d'Aboulfeda (vol. 1, 269 sq. 1848). J. L. E. Dreyer: History of the Planetary
System from Thales to Kepler (p. 245, 249 278 Cambridge, 1906) R.
A. Nicholson: Literary History of the Arabs (359 1907).
An Encyclopedic Scientist.... Al-Kindi
Abu Ysuf Ya'qub ibn Ishaq ibn al-Sabbah al-Kindi
(i. e., of the tribe of Kinda) Latin name, Alkindus. Born in Basra at the
beginning of the ninth century, flourished in Bagdad under al-Ma' mun and
al-Mu'tasim (8l3 to 849), persecuted during the orthodox reaction led by
al-Mutawakkil (841 to 861); died c. 873. "The philosopher of the Arabs;"
so-called probably because he was the first and only great philosopher
of the Arab race. His knowledge of Greek science and philosophy was considerable.
He made a deep study of Aristotle from Neoplatonic point of view. Relatively
few of his numerous works (270?) are extant. They deal with mathematics,
astrology , physics, music, medicine, pharmacy, and geography. He wrote
four books on the use of the Hindu numerals. Many translations from the
Greek into Arabic were made or revised by him or under his direction. He
considered a1chemy as an imposture. Two of his writings are especially
important: "De aspectibus," a treatise on geometrical and physiological
optics (largely based on Euclid, Heron, Ptolemy; no dioptrics), which influenced
Roger Bacon, Witelo, etc.; "De medicinarum compositarum gradibus," an extraordinary
attempt to establish posology on a mathematical basis. He is the earliest
Muslim .writer on music whose works have come down to us; they contain
a notation for the determination of pitch. Many writings of his were translated
into Latin by Gherardo da Cremona. His influence was long felt and
Cardano considered him as one of the twelve greatest minds.
Text and Translation - The De medicinarum compositarum
gradibus investigandis libellus was published in Strassburg (1531) Die
philosophischen Abhandlungen des al-Kindi. Zum ersten Male hrg . von Albino
Nagy (Beitr. zur Gesch. d. Philos. des Mittelalters, II, 5, 118 p., Munster,
1897.
Geometers Al-Hajjaj ibn Yusuf was the first translator of Euclid's "Elements 'into Arabic . Al-'Abbas wrote commentaries upon them . Abu Sa'id al-Darir wrote a treatise on geometrical problems. Two of the Banu Musa, Muhammad and Hasan, were especially interested in geometry; the third, Ahmad, was a student of mechanics. Books on the measurement of the sphere, the trisection of the angle, and the determination of two mean proportionals between two given quantities are ascribed to them. They discovered kinematical methods of trisecting angles and of drawing ellipses.
Arithmeticians and Algebraists The Jewish astrologer Sahl ibn Bishr wrote a treatise on algebra. The greatest mathematician of the time, and, if one takes all circumstances into account, one of the greatest of the times was al-Khwarazmi. He combined the results obtained by the Greeks and the Hindus and thus transmitted a body of arithmetical and algebraic knowledge which exerted a deep influence upon mediaeval mathematics. His works were perhaps the main channel through which the Hindu numerals became known in the west. The philosopher al-Kind1 wrote various mathematical treatises, including four books on the use of Hindu numerals. This may have been another source of Western knowledge on the subject. In any ease, the Arabic transmission eclipsed the Hindu origin, and these numerals were finally known in the West as Arabic numerals.
Translators of the "Almagest" The earliest translator of the "Almagest" into Arabic was the Jew Sahl al-Tabari. Another translation was made a little later (in 829), on the basis of a Syriae version, by al-Hajjaj ibn Yusuf.
Astronomers and Trigonometricians Ahmad
al-Nahawandi made astronomical observations at Jundishapur and compiled
tables. The Caliph al-Ma'mun built an observatory in Baghdad and another
in the plain of Tadmor. His patronage stimulated astronomical observations
of every kind. Tables of planetary motions were compiled, the obliquity
of the ecliptic determined, and geodetic measurements carefully made.
Al-Khwarizmi was one of the first to compute
astronomical and trigonometrical tables. Habash al-Hasib seems to have
been one of the greatest astronomers working for al-Ma'mun. He edited three
astronomical tables, seems to have been the first to determine the time
by an altitude, and introduced the notion of shadow (umbra versa) corresponding
to our tangent.
He compiled a table of tangents, probably
the earliest of its kind. Sanad ibn 'Ali was the chief of al-Ma'mun's astronomers.
Astronomical tables were compiled by him and by Yahya ibn abi Mansur, it
is probable that those tables (and those of Habash already quoted) were
due to the cooperative efforts of many astronorners. Observations were
made by the geometers al-'Abbas, 'Ali ibn 'Isa al-Asturlabi, Yahya ibn
abi Mansur, al-Marwarrudhi, and al-Khwarizmi;
also the observations made by al-Dinawari in 845-50 in Ispahan.
The geometer Abu Sa'id al Darir wrote a treatise
on the drawing of the meridian.
'Al. ibn 'Isa al-Asturlabi was a famous maker
of instruments; he wrote 3 treatise on the astrolabe. But by far the most
notable of that distinguished company was al-Fargham (Alfraganus). He was
apparently the first Muslim to write a : comprehensive treatise on astronomy.
That treatise was very popular until the fifteenth century; it influenced
not only the Muslim, but also, through Latin and Hebrew translations, the
Christian and Jewish astronomers.
Astrologers It is safe to assume that every astronomer was also, incidentally an astrologer. There are a few popular men, throughout the Middle Ages, who were chiefly if not exclusively concerned with astrology, they contributed powerfully to its debasement, The main astrologers of this period were 'Umar ibn al-Farrukhan and his son Muhammad Abu Ma'shar (Albumasar), Sahl ibn Bishr, and Abu 'Ali al-Khaiyat.
Al-Hajjaj ihn Yusuf
Al-Hajjaj ihn Yusuf ibn Matar. Flourished
some time between 786 and 833. probably in Baghdad. The first translator
of Eucelid's "Elements" into Arabic and one ef the first translators of
the "Almagest." kitab al-mijisti, hence our word almagest). Al-Hajjaj's
translation of the Almagest was made in 829-8.90 on the basis of
a Syriac version (by Sergios of Resaina'' (first half of sixth century).
A later adaptation of the Almagest was made by Abu-l-Wafa' (second half
of tenth century) .
He twice translated the "Elements'' of Euclid,
first under Harun al-Rashid then again under al-Ma'mun.
Al-'Abbas ibn Sa'id
al-'Abbas ibn Sa'id al-Jauhari. Flourished
under al-Ma mun. Muslim mathematician and astronomer. He took part in the
astronomical observations organized at Baghdad in 829.30 and at Damaseus
in 832-833. He wrote commentaries on Euclid's Elements.
H. Suter: :Mathematiker (12, 1900)
Abu Sa'id al-Darir
Abu Sa'id al-Darir al-Jurajani. who died in
845/6; thus he flourished in the first half of the ninth century.
Muslim astronomer and mathematician. He wrote a treatise on geometrical
problems and another on the drawing of the meridian.
H. Suter: :Mathematiker (12, 1900).
Al.-Khwarizmi
Abu 'Abdallah Muhammad ibn Musa al-Khwarizmi.
The last-mentioned name (his nisba) refers to his birthplace, Khwarizm,
modern Khiva, south of the Aral Sea. It is under that name that he was
best knoxvn, as is witnessed by the words algorism and augrim (Chaucer)
derived from it. Flourished under al-Ma'mun, caliph from 813 to 833, died
c. 850. Muslim mathematician, astronomer, geographer. One of the greatest
scientists of his race and the greatest of his time. He syneretized Greek
and Hindu knowledge. He influenced mathematical thought to a greater extent
than any other mediaeval writer. His arithmetic (lost in Arabic; Latin
translation of the twelfth century extant) made known to the Arabs and
Europeans the Hindu system of numeration. His algebra, Hisab al-jabr wal-muqabala,
is equally important. It contains analytical solutions of linear and quadratic
equations and its author may be called one of the founders of analysis
or algebra as distinct from geometry. He also gives geometrical solutions
(with figures) of quadratic equations, for ex., X2 + 1OX = 39,
an equation often repeated by later writers. The Liber ysagogarum Alchorismi
in artem astronomicam a magistro A. [Adelard of Bath ?] compositus!' deals
with arithmetic, geometry. music, and astronomy; it is possibly a summary
of al-Khwarzmi's teachings rather than an original work. His astronomical
and trigonometric tables, revised by Maslama al-Majrti (Second half of
tenth century), were translated into Latin as early as l126 by Adelard
of Bath. They were the first Muslim tables and contained not simply the
sine function but also the tangent (Maslama's interpolation). Al-Khwarizmui
probably collaborated in the degree measurements ordered by al-Ma'nun.
He improved Ptolemy's geography, both the text and the maps (Surat al-ard,
"The Face of the Earth").
General Studies Fihrist (p. 274 and comm.).
H. Suter: Die Mathematiker und Astronomen der Araber (l0, 1900);
Nachtrage (158-160, 1902). L. C. Karpinski's edition of the Algebra (1915.)
Sahl Al-Tabari
Also called Rabban al-Tabari, meaning the Rabbi
of Tabaristan. Flourished about the beginning of the ninth century.
Jewish astronomer and physician. The first translator of the Almagest into
Arabic.
H. Suter: Die Mathematiker und Astronomen der
Araber (l0, 1900); M. Steinschneider: Die arabische Literatur der Juden
(23-34, Frankfurt, 1902).
Ahmed Al-Nahawandi
Ahmad ibn Muhammad al-Nahawandi. Flourished at Jundishapur at the time of Yahva ibn Khalid ibn Barmak, who died in 802-3; he himself died c. 835 to 845. Muslim astronomer. He made astronomical observations at Jundishapur and compiled tables called the comprehensive (Mushtamil).
H. Suter: Die Mathematiker und Astronomen der Araber (l0, 1900)
Habash Al-Hasib
Ahmad ibn 'Abdallah al-Marwazi (i. e., from
Merv) Habash al-Hasib (the calculator). Flourished in Baghdad; died
a centenarian between 864 and 874. Astronomer under al-Ma'mun and
al-Mu'tasim. (He observed from 825 to 835) He compiled three astronomical
tables: the first were still in the Hindu manner; the second, called the
'tested" tables, were the most important; they are likely identical with
the "Ma'munic" or "Arabic" tables and may be a collective work of al-Ma'mun's
astronomers; the third, called tables of the Shah, were smaller. Apropos
of the solar eclipse of 829, Habash gives us the first instance
of a determination of time by an altitude (in this case, of the sun); a
method which was generally adopted by Muslim astronomers.
He seems to have introduced the notion of "shadow," umbra (versa),
equivalent to our tangent, and he compiled a table of such shadow which
seems to be the earliest of its kind.
The astronomer Sanad ibn 'Ali is said to have made investigations on specific gravity. Al-Kindi wrote a treatise on geometrical and physiological optics; he criticized alchemy. His writings on music are the earliest of their kind extant in Arabic; they contain a notation for the determination of pitch. Among the works ascribed to the Banu Musa, is one on the balance.
Islamic Geography, and Geology
Al-Ma'mun ordered geodetic measurements, to
determine the size of the earth, and the drawing of a large map of the
world. The mathematician al-Khwarizmi wrote a geographical treatise, entitled
the Face of the Earth, which was essentially revised edition of Ptolemy's
geography; it included maps. Sulaiman the
Merchant traveled to the coast-lands of the Indian Ocean and to China;
an account of his journeys was published in 851.
Some idea of Muslim views on minerals may
be obtained in the so called "Lapidary" of Aristotle. That compilation
is probably of Syriac and Persian origin, and one may tentatively place
the Arabic version in the first half of the ninth century. 'Utarid's lapidary,
the earliest work of its kind in Arabic, dates probably from the same time.

Arabic Medicine
There is nothing to report in this time
on either Latin or Chinese medicine, and that my account of Byzantine medicine
is restricted to a reference to Leon of Thessalonica. Practically all the
medical work of this period was due either to Japanese or to Arabic-speaking
physicians. To consider the latter first, I said advisedly "Arabic speaking"
and not "Muslim," because out of the eight physicians whom G. Sarton
mentioned as the most important, six were Christians, most probably Nistorians.
Of the two remaining, one was a true Arab, the other a Persian. A great
part of the activity of these men was devoted to translating Greek medical
texts, especially those of Hippocrates and Galen, into Syriac and into
Arabic. All of these translators were Christians, the most prominent being
Ya'hya ibn Batriq, Ibn Sahda, Salmawaih
ibn Bunan, Ibn Masawaih, and Ayyub al-Ruhawi.
Jibril ibn Bakhtyashu'
collected Greek manuscripts and patronized the translators, but he also
wrote some medical works. Salmawaih ibn
Bunan showed that the use of aphrodisiacs,
always so popular in the East, was dangerous. The greatest of all these
physicians was the Christian Ibn Masawaih
(Mesue Major). He dissected apes and composed
various anatomical and medical writings, notably the earliest ophthalmological
treatise extant in Arabic and a collection of aphorisms. The philosopher
al-Kindi
wrote medical works also, the most important being one wherein he tried
to establish posology on a mathematical basis. The Persian 'Ai
al-Tabari completed, in 850, a medical
encyclopaedia entitled Paradise of Wisdom.
Ibn Sahda
Flourished at al-Karkh (a suburb of Baghdad),
probably about the beginning of the ninth century. Translator of medical
works from Greek into Syriac and Arabic. According to the Fihrist he translated
some works of Hippocrates into Arabic. According to Hunain ibn Ishaq, he
translated the "De sectis" and the "De pulsibus ad tirones" of Galen into
Syriac.
Max Meyerhof: New Light on Hunain ibn Ishaq
(Isis, VIII, 704, 1926).
Jabril Ibn Bakhtyshu
Grandson of Jirjis ibn JibriI, q. v., second
half of eighth century; physician to Ja'far the Barmakide, then in 805-6
to Harun al-Rashid and later to al-Ma'mun; died in 828-29; buried in the
monastery of St. Sergios in Madain (Ctesiphon). Christian (Nestorian) physician,
who wrote various medical works and exerted much influence upon the progress
of science in Baghdad. He was the most prominent member of the famous Bakhtyashu'
family. He took pains to obtain Greek medical manuscripts and patronized
the translators.
F. Wustenfeld: Arabische Aerzte (15-16, l840).
L. Leclere: Medecine arabe (vol. 1, 99-102, 1876). M. Meyerhof: New Light
on Hunain (Isls, VIII, 717, 1926).
Salmawaih Ibn Buan
Christian (Nestorian) physician, who flourished
under al-Ma'mun and al-Mu'tasim and became physician in ordinary to the
latter. He died at the end of 839 or the beginning of 840. He helped
Hunain to translate Galen's Methodus medendi and later he patronized Hunain's
activity. He and Ibn Masawaih were scientific rivals. Salmanwaih realized
the perniciousness of aphrodisiacs.
Leclerc: Medecine arabe (vol. 1, ll8, 1876).
M. Meyerhof: New Light on Hunain (Isis, VIII, 71S, 1926).
Ibn Masawaih
Latin name: Mesue, or, more specifically, Mesue Major; Mesue the Elder. Abu Zakariya Yuhanna ibn Masawaih (or Msuya). Son of a pharmacist in Jundishapur; came to Baghdad and studied under Jibrll ibn Bakhtyashu'; died in Samarra in 857. Christian physician writing in Syriac and Arabic. Teacher of Hunain ibn Ishaq. His own medical writings were in Arabic, but he translated various Greek medical works into Syriac. Apes were supplied to him for dissection by the caliph al-Mu'tasim c. 836. Many anatomical and medical writings are credited to him, notably the "Disorder of the Eye" ("Daghal al-ain"), which is the earliest Systematic treatise on ophthalmology extant in Arabic and the Aphorisms, the Latin translation of which was very popular in the Middle Ages.
Text and Translation Aphorismi Johannis Damnseeni
(Bologna, 1489. Translation of the al-nawadir al-tibbiya). Many other editions.
In the early editions of this and other works, Joannes [Janus] Damascenu
is named as the author.

