Qusta ibn Luqa

• Name — Qusṭā ibn Lūqā al‐Baʿlabakkī قُسطا ابن لُوقا البعلبکی • Born — 820 • Birthplace — Baalbek, Abbasid Caliphate, now Baalbek District, Beqaa Governorate, Lebanon • Died — 912 (aged 92) • Place of death — Armenia • Period — Abbasid period • Occupation — Physician, scientist, translator • Notable Works — Risalah fī Auja Al Niqris, Rislah fī al Nabidh, Kitāb fī al‐ʿamal bi‐ʾl-kura al‐nujūmiyya, Hayʾat al‐aflāk, Kitāb al‐Madkhal ilā ʿilm al‐nujūm,

Qusta ibn Luqa al-Ba'albakki originated from Baalbek (or Heliopolis), now in Lebanon. A Melkite Christian, he was born in 820 and flourished in Baghdad. He was a philosopher, physician, mathematician and astronomer. He died in Armenia, likely circa 912.

Qusta ibn Luqa produced, personally revised, or supervised the translations of a number of works. These include works by Diophantus, Theodosius of Bithynia's Spherics, On Days and Nights, and On the places of habitation, Autolycus's On the moving sphere and On Risings and Settings, Hypsicles's On Ascensions, works by Aristarchus, Theophrastus’s Meteora, Galen’s catalogue of his books, Hero of Alexandria's Mechanics, and works by John Philoponus. He wrote commentaries on Euclid and a treatise on the armillary sphere. He was a prominent figure in the Graeco-Arabic translation movement that reached its peak in the 9th century. At the request of wealthy and influential commissioners, Qusta translated works on astronomy, mathematics, mechanics and natural science from Greek into Arabic.

More than 60 treatises are attributed to Qusta. He wrote mainly on medical subjects, but also on mathematics and astronomy. Only a small number of his works have been published. The extant editions of medical works show that he was thoroughly acquainted with Hippocratic-Galenic humoral medicine—the theoretical system that constituted the basis of formal medicine in Islam. Qusta's works, many listed in the Fihrist of Ibn al-Nadim, dealt with contemporary science, medicine, astronomy and philosophy. A Latin translation of his work De Differentia Spiritus et Animae was one of the few works not attributed to Aristotle that was included in a list of ‘books to be read by the Masters of the Faculty of Arts, at Paris in 1254, as part of their study of Natural Philosophy. The work was translated by John of Seville (fl. 1140). He wrote a treatise on Nabidh. His Medical Regime for the Pilgrims to Mecca: The Risālā Fī Tadbīr Safar Al-ḥa is available in translation.

Research in 2021 traces the discovery of pulmonary circulation to Qusta's book A Treatise on the Difference Between Spirit and Soul (Arabic: رسالة في الفرق بين الروح والنفس).

Of him Ibn al-Nadim says: "He is an excellent translator; he knew well Greek, Syriac, and Arabic; he translated texts and corrected many translations. Many are his medical writings." Qusta was with Hunayn ibn Ishaq the author who best served Greek culture in the Arab civilization.

He was also involved, with his fellow Christian Hunayn ibn Ishaq, in an epistolary exchange with the Muslim astronomer, Abu Isa Yahya ibn al-Munajjim, who had invited them to embrace Islam. Both refused, and provided their reasons for rejecting al-Munajjim's Islamic faith.

The authorities additionally record the headings Qusṭā ibn Lūqā, Qusṭā albaʻlabakiiy and Qusṭā al-Baʻlabakkī. His recorded language was Arabic. His recorded confession was Christianity.

Qusta ibn Luqa is recorded as physician, mathematician, translator, writer and astronomer.