In the year 762, the caliph al-Mansur traced a circular city onto the Mesopotamian plain and named it Madinat al-Salam, the City of Peace. The world would come to know it by the name of the village that stood on that bend of the Tigris: Baghdad. Within a century it had become the largest city outside China and the stage for an intellectual experiment without precedent. There, under the patronage of the early Abbasid caliphs, scholars undertook the systematic translation into Arabic of almost the entire scientific and philosophical inheritance of Greek antiquity, together with Persian and Indian sources. It was, in all likelihood, the greatest translation enterprise history had yet seen.
A material detail made it possible. Around 751, after contact with prisoners from Central Asia, the Abbasids learned the manufacture of paper, far cheaper than parchment. A market of stationers and booksellers opened in Baghdad, and the book ceased to be a luxury object and became a working tool. On that infrastructure the translation movement flourished, sustained across three reigns: that of al-Mansur, that of Harun al-Rashid —whose palace library was known as Khizanat al-Hikma, the "treasury of wisdom"— and, above all, that of al-Ma'mun (who reigned from 813 to 833), under whom the undertaking reached its peak. Tradition holds that al-Ma'mun one night dreamt of Aristotle and, on waking, sent emissaries to Byzantium to buy Greek manuscripts. Legend or not, we know those missions were real.
The central figure of that effort was Hunayn ibn Ishaq (c. 809–873), a Nestorian Christian physician born in al-Hira, in southern Iraq, who commanded Arabic, Syriac, Greek and Persian. His contemporaries called him the "sheikh of the translators". He did not translate word for word —a method he judged crude and misleading— but sense for sense, collating as many Greek manuscripts as he could gather to establish the best text before rendering it. He also ran a genuine school: he or his pupils first moved from Greek into Syriac, his nephew Hubaysh and his son Ishaq carried it from Syriac into Arabic, and Hunayn revised the result. From his workshop came close to a hundred and thirty works of the physician Galen, Plato's Timaeus, treatises of Aristotle and the pharmacology of Dioscorides. Other teams, such as that of the mathematician Thabit ibn Qurra (826–901), fixed Euclid, Archimedes and Ptolemy's Almagest in Arabic. Some patrons, it is said, paid for translations by weight: the finished book's weight in gold.
A historian's prudence is called for, however. The phrase "House of Wisdom" (Bayt al-Hikma) today conjures a great academy of marble, but specialists —Dimitri Gutas foremost among them— warn that the sources are scarce and ambiguous: Hunayn himself never names it. It was most probably a palace library and archive, and the bulk of the translating was done across a wider network of private patrons, powerful families and court physicians spread through the city. The myth of the single institution matters less than the incontestable fact: for two centuries, Baghdad translated.
The legacy far outran its authors. Many Greek originals were later lost in their first language and survive only thanks to those Arabic versions. And from there, centuries later, that learning set out on a second journey: when Latin Europe rediscovered Aristotle, Euclid or Ptolemy, it often did so by translating from Arabic —most notably at the Toledo School of Translators. The manuscripts of Baghdad, sacked by the Mongols in 1258, had already sown a field that would ripen in the Renaissance.
From that library to today
The lesson of the House of Wisdom has not aged: one civilisation does not inherit another's knowledge by sympathy, but because someone sits down to translate it with rigour. Those Baghdad translators understood that rendering a text is not swapping words but guaranteeing that two languages say the same thing exactly. It remains, to this day, the sworn translator's craft: to attest that a document and its translation are, to whoever reads them, the same text.