The ūMūsāthree brothers Abū Jaʿfar, Muḥammad ibn Mūsā ibn Shākir (before 803 – February 873); Abū al‐Qāsim, Aḥmad ibn Mūsā ibn Shākir (d. 9th century) and Al-Ḥasan ibn Mūsā ibn Shākir (d. 9th century), were Persian scholars who lived and worked in Baghdad. They are collectively known as the Banū Mūsā (, "Sons of (or Moses)").
The Banū Mūsā were the sons of Mūsā ibn Shākir, who was an employee of al-Ma'mun, a son of the Abbasid caliph Harun al-Rashid. After their father's death, the brothers received an education under al-Ma'mun’s direction, and were enrolled at the House of Wisdom in Baghdad. There they undertook the translation of ancient Greek works acquired from Byzantium, which they used to develop their own technological, mathematical and astronomical ideas. They were some of the earliest scholars to adopt Greek mathematics, but innovative in their approach to the concepts of area and circumference by expressing them using numerical values instead of ratios. They made geodesic measurements to determine the length of a degree of latitude, and so obtained a relatively accurate value for the circumference of the Earth.
The Banū Mūsā wrote almost 20 books, all but three of which are now lost. The most important of all their works was a treatise on geometry, ("Book on the Measurement of Plane and Spherical Figures"), which was used extensively by medieval mathematicians. Their most famous extant work (of which the oldest and most reliable copy is in the Topkapi Sarayi in Istanbul) is ("Book of Ingenious Devices"). It describes 100 inventions, many of which were pouring vessels, intended to entertain party guests. Some of their innovations, such as those that involved fluid pressure variations and valves, remained unsurpassed until the modern period. One of those inventions includes an automatic flute player that may have been the first programmable machine or computer.
Biographical details
Early years
Moḥammad, Aḥmad, and Ḥasan were the three sons of Mūsā ibn Shākir. They are always listed in sources in what is assumed by scholars to be their order of seniority. A Persian from Khorasan, Mūsā had been a highwayman, but became known as an astronomer. According an account by the medieval Egyptian historian Al-Qifti, Mūsā ibn Shākir was known to leave part of the way through the Friday prayer to rob travellers, before returning to the mosque before the praying was finished.
Musa befriended al-Ma'mun, a son of the Abbasid caliph Harun al-Rashid who was staying in Merv. Al-Maʾmūn, who became caliph in 813, employed Musa as an astronomer. According to one story, al Ma’mun saw the Greek polymath Aristotle in a dream telling him about the importance of natural philosophy, which resulted in al-Ma’mun supporting the work then being done by scholars, during what has been called by some historians of science as the Islamic Golden Age.
After their father's death, the three orphaned children were cared for at the court of al-Maʾmūn, who made the senior Baghdad official Ishaq ibn Ibrahim al-Mus'abi their guardian. Al-Ma’mun recognized their abilities, and enrolled them in the House of Wisdom, an institution created by him as a centre for collecting, translating and studying books from other lands. In Baghdad, where they apparently lived for the rest of their lives, the three brothers studied geometry, mechanics, music, mathematics and astronomy, trained by a senior court astrologer, Yaḥyā bin Abī Manṣūr.
Accomplishments under the Abbasid Caliphate
The Banū Mūsā assisted al-Ma'mun's in his obsession to obtain and translate works from Greek into Arabic. They sent for Greek texts from the Byzantines, or travelled themselves to Byzantium to acquire them. During their working lives they used their wealth and energy towards the translation of these works. On his way home to Baghdad from Byzantium, Muhammad met and recruited Thābit ibn Qurra, a money changer from Harran. Thābit went on to make important discoveries in algebra, geometry, and astronomy.
Under the direction of al-Ma'mun, the Banū Mūsā worked with the most talented men available, including al-Khwarizmi, al-Kindi, Al-Ḥajjāj ibn Yūsuf ibn Maṭar, and the mathematician and translator Hunayn ibn Ishaq, who became a close friend of one of the brothers, Muhammad. Of the translators, three were paid about 500 dinars a month. None of the brothers were medically trained, and relied upon Ishaq bin Hunayn and Thabit bin Qurra to translate Greek medical works. They exchanged ideas with other experts, including the astrologer Abu Ma'shar al-Balkhi, with whom Muhammed was in continuous contact.