Regiomontanus was the pen name of Johann Müller, responsible for what some call the "rebirth of trigonometry" during the century following his death. Although he was a practicing astrologer , he also was one of the first Europeans to closely observe certain celestial objects and events previously tied to superstitions. Regiomontanus published his own and others' translations of classical and Arabic texts with his then novel printing press. He predicted that sailors would one day be able to navigate according to the position of the moon, a process that eventually did arise during the Age of Exploration. (Some speculate that Regiomontanus' early death prevented him from anticipating Copernicus.) Once dismissed as a comparatively undisciplined technician, Regiomontanus is now recognized as the West's answer to Nasir al-Din or Nasir Eddin, having brought plane and spherical trigonometry within the purview of pure mathematics and out of its apprenticeship to...