Abu al-'Abbas Abdallah al-Ma'mun ibn al-Rashid

786-833

Persian Caliph

Al-Ma'mun was the seventh Abbasid caliph and a great patron of the sciences in the Islamic world. He established an influential scientific academy in Baghdad where Arab scholars made important contributions to mathematics, astronomy, and others fields. Under Al-Ma'mun's sponsorship, the translation of Greek and Hellenistic scientific texts into Arabic reached its peak.

Al-Ma'mun was born in Baghdad in 786 to the celebrated Caliph Harun ar-Rashid and an Iranian concubine. Al-Ma'mun's younger half-brother, al-Amin, was born to one of ar-Rashid's Arabic wives. Ar-Rashid selected al-Amin as his successor to the caliphate in Baghdad; but Al-Ma'mun was to have suzerainty over the eastern provinces, wielding his power from Merv in Khorasan (now Turkmenistan). However, at the death of ar-Rashid in 809, Al-Ma'mun rejected al-Amin's right of succession and a merciless civil war ensued. Al-Ma'mun besieged his brother in Baghdad in April 812. The city fell in September of the following year, and al-Amin was killed.

At the time al-Ma'mun assumed control of the Abbasid empire, Islam was deeply divided over who was Mohammed's rightful heir. Sunnites accepted the Abbasid caliphs, while Shiites championed the descendants of Ali, Mohammed's cousin and brother-in-law. Al-Ma'mun sought to reconcile these groups by designating 'Ali ar-Rida, a descendant of Ali, as his heir. This failed to mollify Shiite extremists and outraged Sunnite partisans. Rebellion soon erupted in Baghdad. Al-Ma'mun quickly quelled the uprising, but 'Ali ar-Rida mysteriously died in August 818, most likely poisoned by al-Ma'mun.

After restoring order, al-Ma'mun abandoned his policy of reconciliation. Instead, he sought to promote acceptance of a more flexible caliphate by imposing Mu'tazili doctrine on his subjects. Supporters of Mu'tazilism emphasized rational methods of inquiry and borrowed freely from Greek and Hellenistic philosophers. In keeping with the spirit of this movement, al-Ma'mun established a scientific academy at Baghdad called the House of Wisdom (Bayt al-Hilkmah).

The academy's library was the most ambitious institution of its kind since the foundation of the great library at Alexandria. Al-Ma'mun stocked it with every available book and even sent an expedition to Byzantium to acquire additional manuscripts. He encouraged the translation of philosophical and scientific works from Greek and Syriac into Arabic.

Hunayn ibn Ishaq al-Ibadi (808-873) was the director of the House of Wisdom. He primarily translated medical texts, especially those of Hippocrates (460?-370? b.c.) and Galen (130-200?), while his son translated Euclid's (330?-260? b.c.) Elements and Ptolemy's (second century a.d.) Almagest. Thabit ibn Qurra (836-901) was the principal translator of mathematical texts.

The academy's observatory attracted Islam's greatest astronomers. Al-Khwarizmi (780?-850?) worked there and produced an important set of astronomical tables as well as his celebrated work on algebra. Al-Farghani (800?-870?) also worked there. His Elements of Astronomy did much to spread the more elementary parts of Ptolemy's work.

A major impetus for the academy's astronomical work came from religious observances. Various problems in mathematical astronomy, specifically spherical geometry, were addressed in attempting to accurately determine the qible, the location or direction of Mecca, which was necessary for Muslim prayer. Al-Ma'mun also commissioned his astronomers to determine the Earth's size. After measuring a degree of the meridian in the plain of Palmyra and another location, it was determined that the Earth's diameter was 6,500 mi (10,461 km), approximately 18% too small. Al-Ma'mun's astronomers also redeterimined the value for the inclination of the ecliptic. A large map of the world was also produced for al-Ma'mun using a crude cylindrical projection.

Al-Ma'mun died at Tarsus in 833 while campaigning against the Byzantines. Though his Mu'tazili reform served to undermine the authority of the Abbasid caliphs, the translations, commentaries, and original research produced by his House of Wisdom contributed greatly to the development of science.

STEPHEN D. NORTON