Mathematical Astronomy in Copernicus’ De Revolutionibus

When I first laid out the framework for A History of Ancient Mathe­ matical Astronomy, I intended to carry the discussion down to the last applications of Greek astronomical methodology, i. e. Copernicus, Brahe, and Kepler. But as the work proceeded, it became evident that this plan was much too ambitious, and so I decided to terminate my History with late antiquity, well before Islam. Nevertheless, I did not discard the running commentary that I had prepared when studying De revolutionibus in