'The Almagest' by Ptolemy (2nd century AD) was one of the most influential scientific works in history. It described the Ptolemaic system of astronomy and geography. Before this edition appeared it was only know in a poor Arabic translation. Georg von Peurbach (1423-1461) started editing and translating the work but died after completing the first four books. The work was completed by his pupil Johannes Regiomontanus (1436-1476). This volume reintroduced Greek astronomy and its theories of the universe to the west, in Latin, the language all scholars could read. This is the frontispiece and shows an armillary sphere, and below it, Ptolemy sitting on the left with Regiomontanus facing him on the right, a portrait that is considered authentic.
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