Every time you run a search, open an app, or follow a digital map, you are using a concept named after a ninth-century scholar. Muhammad ibn Musa al-Khwarizmi's Latinized name became the word "algorithm," and his book on calculation gave us "algebra." Born around 780 to a Persian family from Khwarazm, he rose to head the library at Baghdad's House of Wisdom, the Abbasid Caliphate's state-funded answer to Silicon Valley, where the smartest people alive translated and fused Greek geometry, Indian numerals, and Babylonian astronomy.

This episode digs into how one synthesizer wrote the source code of the modern world: an algebra invented in plain prose with no equal signs, no plus symbols, and no letter x, built to solve canal-digging, land surveys, and Islamic inheritance law. It follows his correction of Ptolemy's maps, the star-sighting network that recalculated the Mediterranean, and the unsettling fact that his most influential book survives only because someone translated it into Latin before the original vanished.

• How Baghdad's House of Wisdom became the 9th-century Bell Labs, and how al-Khwarizmi ended up running its library
• Al-jabr and al-muqabala: the restoration-and-balancing moves that became the algebra you learned in school
• Math without symbols: solving quadratic equations as word riddles about dividing ten into two parts
• Fixing Ptolemy: shrinking the Mediterranean by 13 degrees and proving the Indian Ocean wasn't landlocked
• The lost original: why the book that brought Hindu-Arabic numerals to Europe survives only in Latin