90
also acted as an academy for
scholars and a center for the
translation of key scientific works
into Arabic. Among its leading
scholars were Hunayn ibn Ishaq
(808–873), a Nestorian Christian
from al-Hira in Iraq, who translated
more than 100 mostly medical and
philosophical works; and Thabit ibn
Qurra, a member of a pagan sect
known as the Sabaeans, who
translated Elements, Euclid’s
great work on geometry, and the
Almagest, Ptolemy’s key work
on astronomy.
Translation became a highly
prestigious endeavor. One Arab
patron paid an extravagant 2,000
dinars a month to ensure his
association with a translation of
a work by the Greek physician
Galen (a dinar, made of pure gold,
weighed the same as 72 grains of
barley). Within around 150 years,
almost all of the key Greek textsthat had been discovered had been
rendered into Arabic. Many of them
were not available in Western
Europe at all, and even if they had
been, knowledge of Greek had all
but disappeared there. The Muslim
world was therefore well set by
around 850 to build on the scientific
traditions of Classical and Hellenistic
Greeks transmitted and developed
under the Roman Empire—and to
acquire a centuries-long lead over
Christian Western Europeans.Complex calculations
An understanding of mathematics
and astronomy is essential to the
calculation of the times at which
Muslims must observe their five
daily prayers (times that varied
widely across the vast Islamic
Empire), therefore both disciplines
were studied assiduously. Another,
separate, intellectual tradition
contributed to the developmentTHE FOUNDING OF BAGHDAD
of these calculation techniques,
arriving in 771 with a delegation of
Hindu scholars. The scholars were
visiting al-Mansur’s court (which in
itself illustrates the comparative
openness and tolerance of theJews and Christians...
translate these scientific books
and attribute them to their
own people... when they are
indeed Muslim works.
Muhammad ibn Ahmad
Ibn Abdun
Legal scholar (early 12th century)Arabic versions
of classical Greek
texts ensured the
survival of ancient
knowledge.Mathematical
advances made
possible the use
of algebra and
decimal places.Philosophical and
scientific works by
Aristotle and Plato
came from conquered
Greek lands.Hindu numerals,
including the
number zero,
came from India.The House of Wisdom played host to
scholars who translated Latin and Greek
works into Arabic. In doing so, they built upon
classical knowledge and made breakthroughs
in fields such as mathematics and medicine.
House
of WisdomUS_086-093_Harun_al_Rashid.indd 90 15/02/2016 16:41
91
early Abbasids), and brought with
them India’s relatively advanced
mathematics, including the use of
trigonometry to help solve algebraic
equations. Crucially, the Hindu
mathematicians also employed
a decimal notation, which one of the
members of the House of Wisdom,
Al-Khwarizmi (c.780–830), adopted
and described in The Book of
Addition and Subtraction According
to Hindu Calculation.
Furthermore, Al-Khwarizmi also
explained a method of calculating
the square roots of numbers, and
pioneered work on algebraic
equations. He and his fellow
scholars made rapid strides in
geometry, taking as their starting
point Euclid’s and Archimedes’s
work on spheres and cylinders.Astronomy and medicine
Al-Khwarizmi compiled the first
known tables of daily prayer times
at Baghdad, his calculations
assisted by direct astronomical
observation. The early Islamic
astronomers drew from Ptolemy’s
Almagest, adopting his view that
the Earth was at the center of the
solar system, and that the planets
rotated around it along the lines
of eight spheres. They also learned
from Hindu astronomers, translating
and perfecting Indian zij, or tables of
planetary positions, and continued
to refine Ptolemy’s system, only
occasionally (as in the work of the
10th-century astronomer al-Biruni)
toying with a heliocentric system
that had the sun at its center. Their
calculations were made simpler
when in the mid-eighth century
they adopted the astrolabe, aninstrument in which the celestial
sphere was projected onto a flat
plane marked with latitude and
longitude lines.
By the 13th century, Islamic
astronomy was at its zenith, and
in 1259 a great observatory was
constructed at Maragha in eastern
Iran. Here Nasr al-Din al-Tusi
and his successors made fine
adjustments to account for slight
discrepancies in the orbit of the
planets, assisted by mechanical
clocks that enabled them to record
their observations in fine detail.
Muslim scholars made advances in
many other areas, too, first building
on the base of Greek manuscripts
translated into Arabic, and then
making their own discoveries. They
did not accept the theories of the
ancients uncritically: al-Haythem
(died 1039) produced a key work,
the Book of Optics, in which he
speculated that sight was the result
of light traveling from an object to
the eye, rather than the other way
around as Ptolemy had theorized.
Arab physicians continued to make
progress, combining their practicalTHE MEDIEVAL WORLD
observations with theoretical
analysis. Al-Razi (died 925)
produced the first description of
smallpox and measles, as well as
compiling a medical compendium
that began a tradition of such
encyclopedias, culminating in
the Canon of Medicine by ibn Sina
(who was known as Avicenna in
the West). Composed around 1015,
it included separate sections for
diseases that are specific to one
body part, and those that afflict
the body as a whole.Islamic science spreads
The Islamic expansion that began
in the mid-7th century not only
absorbed ancient centers of
learning such as Alexandria, but
also brought the Muslim world to
the fringes of Western Europe
through the conquest of Spain
(from 711) and Sicily (from 827).
A tradition of Islamic learning
embedded itself in both areas,
and particularly in the Iberian
Peninsula, known to the Arabs as
al-Andalus. The court established
there in 756 by Abd ar-Rahman I, ❯❯The Canon of Medicine by ibn
Sina or Avicenna (980–1037) set the
standard for medicine in the Islamic
world and medieval Europe, and
remained an authority for centuries.US_086-093_Harun_al_Rashid.indd 91 15/02/2016 16:41