When the Abbasids founded Baghdad in 762, the transfer of world knowledge into Arabic became a project of state. Begun under caliph al-Mansur, expanded under Harun al-Rashid, and brought to its peak under his son al-Ma'mun (r. 813–833), the translation movement was organised around the Bayt al-Hikma — the House of Wisdom — in Baghdad. Whether the institution was a library, an academy, or a palace bureau is still debated; what is not debated is the scale of its output. Greek, Syriac, Persian, and Sanskrit works were rendered into Arabic with a thoroughness that set the philosophical agenda of the next millennium.

Two generations of translators carried the work. The first is represented by the Syriac Christian physician Hunayn ibn Ishaq (809–873), who brought the medical corpus of Galen and most of Aristotle's logical works into Arabic and turned translation itself into a philological discipline. The second is represented by the Muslim philosopher al-Kindi (801–873), who along with translation wrote commentaries on Aristotle and Plotinus that settled philosophy into the Arabic tongue.

The House of Wisdom's reach extends well beyond a single library. The terminology it forged — jawhar (substance), arad (accident), aql (intellect), nafs (soul) — became the metaphysical vocabulary of Islamic philosophy for a thousand years and, through it, of Latin Europe. Al-Farabi, Avicenna, and Averroes all thought atop this corpus; in the twelfth and thirteenth centuries the movement ran in reverse at Toledo and Sicily, as Arabic philosophy passed into Latin — Aquinas' reading of Aristotle rests on a chain whose first link was forged in Baghdad.