Why a Commentary?

The second chapter investigates Galileo’s claim in De motu antiquiora that he had written a commentary on the Almagest ready for publication. Given the absence of such a commentary and Galileo’s general reluctance to write commentaries, it questions why he mentioned it. The chapter examines writings from contemporary mathematicians and astronomers, like Francesco Barozzi, Christoph Clavius, and Giuseppe Biancani, which reveal a strong demand for a Latin commentary on the Almagest. It also discusses Theon of Alexandria’s Greek commentary on the Almagest and the efforts to translate it into Latin, including Giovanni Battista Teofilo’s translation, which was eventually donated to Galileo’s pupil, Vincenzo Viviani.