Thabit ibn Qurra

Thabit ibn Qurra (Abu al-Hasan Thabit ibn Qurra al-Harrani) was a mathematician, astronomer and physician active in the ninth-century Abbasid world. He belonged to the Sabians of Harran (al-Sabi'a) — a Hellenized, star-venerating community of Upper Mesopotamia, distinct from Islam, that prized Greek learning. He was not a Muslim. His first language was Syriac, and he also commanded Greek and Arabic, which made him an ideal bridge between the Greek scientific heritage and the Arabic-reading scholars of Baghdad.

Tradition reports that as a young man he worked as a money-changer in Harran, though some historians doubt this detail. According to the standard accounts, Muhammad ibn Musa — one of the Banu Musa brothers, wealthy patrons of science — passed through Harran, recognized his gifts, and brought him to Baghdad. There he joined and later helped lead a circle of translators, rendering and revising works of Euclid, Archimedes, Apollonius, Ptolemy and others, and producing original studies in geometry, number theory (including amicable numbers), astronomy and statics.

Some biographers add that he returned to Harran, clashed with his own community over his views, was made to recant, and then left for Baghdad; this episode is reported in tradition rather than firmly attested. In Baghdad he enjoyed the patronage of the caliph al-Mu'tadid (reigned 892-902). He died in Baghdad in 901 CE (Safar 288 AH); the sources record the exact day variously as 18 or 19 February. His son Sinan and grandson Ibrahim ibn Sinan continued his scientific line.