Nasir al-Din al-Tusi
Astronomer, mathematician, and ethicist who saved a library from the Mongols and built the observatory that reformed the model of the heavens.
Al-Tusi lived through the Mongol conquest and turned catastrophe into opportunity, persuading the conqueror Hulagu to build him a great observatory at Maragheh with a library of hundreds of thousands of volumes. There he assembled astronomers from across Asia and devised the Tusi couple, a geometric device that improved on Ptolemy and, centuries later, reappeared in the work of Copernicus. He wrote the most influential Persian book on ethics, advanced trigonometry into an independent science, and defended Avicenna's philosophy against its critics. Few minds have been so wide and so exact at once.
Places
Ideas
Words
“The end of philosophy is to order the soul as the astronomer orders the heavens: by measure, not by wish.”
Works
Life & Moments
Born in Tus
Born in the Persian city of Tus, he became a polymath in astronomy, mathematics, and ethics.
The Maragheh Observatory
Persuaded the Mongol conqueror Hulagu to build a great observatory and library, gathering astronomers from across Asia.
The Tusi Couple
Devised a geometric model that improved on Ptolemy and, centuries later, reappeared in Copernicus.
Death in Baghdad
Died after saving libraries from conquest and reforming the heavens with patient measurement.
Influence
Influenced by
- Ibn Sina
Al-Tusi defended Avicenna's philosophy against its critics and carried his thought into a new age.
- Omar Khayyam
Al-Tusi took up Khayyam's attempt to prove Euclid's parallel postulate, and the chain of near-proofs the two advanced fed into the eventual recognition that the postulate is independent.
- Fakhr al-Din al-Razi
Al-Tusi wrote his own commentary on the Pointers expressly to rescue Ibn Sina from Fakhr al-Din's attacks, producing one of the sharpest exchanges in Islamic philosophy, conducted across a century and entirely in the margins of another man's book.
- Al-Biruni
The tradition of precise observation and calculation that al-Biruni represents is the one al-Tusi institutionalized at Maragheh, where an observatory could do systematically what a single scholar had done alone.
