Bodnár István, Chase Michael, Share Michael (eds.). Simplicius: On Aristotle Physics 8.1-5

Bloomsbury Academic, 2011. — 257 p. — (Ancient Commentators on Aristotle).In these chapters of Book 8 of the Physics, Aristotle (384-322 BC) paves the way for introducing, at the end of Book 8, the Prime Mover of the heavens, which along with most Greeks Aristotle took to rotate around the earth. In Chapter 1, he urges against Democritus that an explanation of motion is needed, even if, as he argues in Chapter 2, motion is eternal, despite (Chapter 3) some non-motion. In Chapter 4,1 he argues that a body’s movement must be caused by something distinct from itself, contrary to Plato’s view that soul is self-moving. Taking the particular case of animals, which are popularly thought of as selfmoving, Aristotle says that it is really the soul that moves an animal’s body (8.4, 254b27-33, developed in 8.6, 258a1-b9), along with stimuli from the environment (to periekhon, 8.2, 253a7-20; 8.6, 259b1-20). But what about the natural motion of air and fire upwards and of earth or water downwards? In Physics 2.1, he had distinguished natural motion from the motion of artefacts, by saying that natural objects have an internal source of movement, their nature, whereas artefacts have to be propelled from outside. But in Physics 8.4, a body’s inner nature seems insufficiently distinct from it to satisfy the requirement that what is moved should be moved by something other than itself.