Nasir al-Din al-Tusi

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.