The subject of Aristotle's On the Heavens, Books 3-4, is the four elements of earth, air, fire and water, which exist below the heavens. Book 3, in chapters 1 to 7, frequently criticizes the Presocratic philosophers. Because of this, Simplicius' commentary is one of our main sources of quotations of the Presocratics. Ian Mueller's translation of this commentary gains added importance by enabling us to see the context which guided Simplicius'...