Two Aristotelian puzzles about planets and their Neoplatonic reception

The longevity of Aristotelian natural science consists not so much in the fact that Aristotle’s solutions to puzzles were accepted by generations of philosophers, but by the fact that the presuppositions that made these puzzles look puzzling were. In what follows I consider some Neoplatonic responses to two puzzles that Aristotle poses in De Caelo Book 2, Chapter 12. Both Proclus and Simplicius rejected Aristotle’s solutions to the puzzles he posed. In one case, but not in the other, they also reassessed the relative importance of the presuppositions that created the puzzle.