ABSTRACT
The philosophers are Plato, Aristotle, and Theophrastus, but the concerns are old and familiar ones. A fascination with the stars, their orderly movement and nature, is a conspicuous feature of early Greek philosophy, beginning with Thales himself (see S. White, this volume). So, too, is the preoccupation with first principles, the origins or starting points which govern all subsequent development. For Aristotle, these issues run together, since the only eternal first principles he recognizes are the beings that move the heavenly spheres. But for Theophrastus, this raises a question about the connection of those principles with the sublunary realm, and consequently about the unity of the cosmos. This will become clearer below, when we compare Aristotle’s cosmology with Plato’s.
