Disentangling the Ptolemaic from the Aristotelian

The third chapter examines Galileo’s references to Ptolemy in De motu antiquiora, focusing on Chapters 5 – 7 of the Almagest I. Galileo acknowledges Ptolemy’s importance and accepts his geocentrism, distinguishing it from Aristotle’s views in De caelo. However, he critiques Ptolemy’s failure to explain the Earth’s central position in the world, offering an alternative rationale influenced by Archimedes’ hydrostatics. This chapter highlights how Galileo integrates Ptolemy’s arguments into a new cosmological perspective informed by Archimedes’ theories.